Genes and Diseases

Genes and Diseases 11/11/14 8:28 AM

MENDELIAN GENETICS

Garden pea plants, that were to help with development of Inheritance.

Mathematics – traits, 2 alleles of a gene segregate during gamete

formation.

Law of independent assortment states that alleles for each gene

segregate independently of alleles for other genes.

The laws of probability govern mendelian inheritance

Inheritance patterns may be more complex than simple mendelian

genetics

Many human traits and conditions follow mendelian patterns.

Interested in heredity (dfn: phys or mental characteristics genetically from

one to another generation)

Blending inheritance

Inheritance

Genetic Testing : garden peas, model organism.

Easy and fast to grow, look at many generation

Control fertilization

Able to control, chop of pollen and then feed other plants with said pollen.

Cross pollination

7 traits

shape

colour

pod shape and colour

flower colour

flower and pot position

stem length

o Didn’t look at characters that had 3 or more. Only looked at

2 ~ phenotype

o Worked with pure breeding, true breeding, when the cell

reproduces it produces IDENTICAL offspring

o Looked at short and tall breeding.

o Looked at seed shape, round vs wrinkle. = P generation or

(parent gen) then the next was F1 gen (first felian

generation) then F2

When he crossed seeds, (round vs wrinkle) looked to see the

character (trait) that was expressed in F1 generation. Found in F1

generation that all F1 offspring produced “round” seeds, no

wrinkle.

When he pollinated F1 with F1 = wrinkle. (3:1)

This contradicted hypothesis.

Therefore Dominant and Recessive traits were born!

In the F1 gen, recessive trait disappeared. Whereas when F2

generation were cross bread, it was that (3:1)

When proposed at time, each person has 2 versions of a character of each

trait.

Diploid, 2 copies of a particular of an Allele. (pair of homologous

chromosomes (us)) – can only be 2 different versions.

Allele found in individual = genotype. (genes)

How genes are expressed. ^^

Use a “letter” to represent gene. “R” = dominant “r” = recessive

A diploid gene will have 2 different alleles

Homozygous, are those with same (mendelian) produced (hetero with

cross pollination)

Heterozygous are those with different

Pure breeding individuals, will only produce offspring with phenotype

When cross with F1 -2= characteristic result of offspring. Ratio of

genotype in a phenotype (1:2:1)

From these experiments = Law of Segregation:

There are 2 alleles for a character or trait and they separate to

gametes

During meiosis: alleles segregate

PUNNET SQUARE

Predict types of offspring you would expect from a cross breeding.

Law of segregation:

2 alleles per cell for a particular trait separate independently into

gametes

Law of independent assortment:

How different genes independently separate from one another

when productive cells develop

Separation of pairs of alleles for each gene is independent of

other genes.

o Note that not all genes obey this rule

o Linked genes tend to be inherited together

Using a testcross for unknown genotype 1 trait

Plant with seed, with plant with homozygous recessive.

Seed colour

Yellow seeded plant, with green seeded plant.

When don’t know, always cross with homozygous recessive

Can also do a testcross with 2 traits

Not only seed colour, but seed traits. Looking for colour with pure

breeding

Terminology

Genes: Mendel’s hereditary factors; segment of DNA specifying

RNA or polypeptide

Alleles: alternate forms of a gene, ‘normal’ – wild type

o NB: while we can only have 2 alleles for each gene in a

diploid cell, there may be many possible alleles for a gene,

called multiple allelism.

Genotype: genetic constitution

Phenotype: characteristics that result from genotype and

environment

o Identical twins: same genes, therefore different phenotype

from environment

Locus: position of gene on chromosome.

Always put dominant allele above recessive allele.

The multiplication rule: 2 or more independent events that happen

together (A and B)

Probability: Toss 2 coins and get 2 heads ½ x ½ = ¼

The addition rude: probability of any one or two or more exclusive events

will occur (A or B) is calculated by adding together their individual

probabilities

Toss 2 coins and get 2 heads or 2 tails= ¼ + ¼ = ½

Recessive traits example:

AaBBcc x AaBbCc


CHROMOSOMAL BASIS OF INHERITANCE

Key Concepts

Meiosis, segregation

Genes on the sex chromosome (X and Y)

Sex linked genes (unique patterns)

Linkage – genes of same chromosome

Alterations in chromosomes number and stricter

1800 (late) Mitosis and Meiosis were discovered.

How do we know that genes exist on Chromosomes?

Due to Thomas Hunt Morgan’s experiments with Drosophila (fruit

flies), the link b/w chromosomes and inherited traits was made.

They produce many offspring

A generation can be bred every 2 weeks

Have only 4 pairs of chromosomes

Noticed – wild type (normal) had red eyes

and some that were mutant (white eyes)

In one, mated mutant types with normal type

o F1 gen had red eyes

o Whereas F2 gen 3:1 red:white, but only males had white

eyes.

Therefore eye colour depends on Y (sperm) chromosome.

Regions pair up, X and Y pan in similar (homologous chromosome

in a fashion) in Metaphase

The human chromosome is made up of many genes

Y chromosome is male – SRY (code for male features)

Grasshoppers, Butterfly use the X O system, females have 22 autosomes

XX whereas males have 22 chromosomes O

Chromosomal Basis of Sex, Sex linked, X chromosome or Sex linkage

Extra chromosome (not good)

Double the amount of protein product in X product, one X chromosome is

deleted from each X chromosome. This is called the Barr body. Happens

early on in embryonic development

If a female has a condition trait, she would be a mosaic character. The

other X chromosome would be activated.

Eg: tortoiseshell cats (coat colour is on the X chromosome)

Linked Genes:

Genes on the same chromosome, are called linked genes (nothing to do

with sex linkage)

The alleles in linked genes tend to be inherited together.

Violated assortment

Independent assortment (diagram)

4x of gametes (1/4)

Dihybrid: independent of other gene

Different rules apply for linked genes: alleles cannot separate, therefore

they are inherited together.

How linkage affects inheritance?

Body colour can be inherited with wing size.

Not always the same in every situation.

Non-parental phenotypes

We have similar traits, but are unable to be there due to

evolution.

Pure breeding. Normal winged, with flat visidual wings.

Double heterozygote

Test crossed with a double mutant, = F1 di hybrid = (1:1:1:1)

If genes are on separate chromosome.

Crossing over still occurs, alleles in crossing over.

Recombination occurs

Only small region for crossing over to occur (1+2). Much greater likelihood

to happen in exchange (1 +3)

% of recombinant offspring, created a linkage map. Distances between

genes are called the Centimorgan (cM) = 1% recombinant frequency

Definitions:

Aneuploidy: Deviation from the usual chromosome number

o Usually result from fertilization of gametes in which non-

disjunction occurred.

o Offspring with this condition have an abnormal number of

chromosomes

Polyploidy: more than 2 complete chromosome sets eg: triploidy

(3n) tetraploidy (4n)

Polysomy: more than 2 of a particular chromosome in diploid

cells

Monosomy: only one copy of a particular chromosome in diploid

cells (generic)

Trisomy: three copies of a particular chromosome in diploid cells.

(generic)

Down Syndrome (Trisomy 21)

Down Syndrome is an aneuploidy condition that results from the

3 copies of chromosome 21

Karyotype 47, XX, +21 or 47, XY, +21

It affects about 1/650 children AUS

Human Oocytes are held in prophase 1 from birth to ovulation

Complications: all of have mental retardation, early Alzheimer’s, problems

with hearing, growth issue, higher incidences of leukemia, males tend to

be infertile.

Aneuploidy of sex chromosome

Klinefelter’s Syndrome: is result of an extra chromosome in a male,

producing XXY individuals, 1/1000 males, karyotype 47

Some female characteristics

Fail to produce normal amounts of testosterone

Monsomy X, called Turner syndrome. Produces XO females, who are

usually sterile and need hormone treatment for sex organs to mature

It is the only known visible monosomy in humans,

Karyotype 45, XO

Also have alterations in chromosome structure (can break, swap over etc)

Deletion: removes a chromosomal segment

Duplication: repeats a segment

Inversion: reverse a segment within a chromosome

Translocation: moves a segment form one chromosome to a non-

homologous chromosome.

One condition that results in a “missing” or “deleted” part of a

chromosome is called “Cri du chat” (cry of the cat) deleted vocal chord

Deletion of the P arm in chromosome 5 (5p-)

Child is born with this syndrome mentally retarded and has a

catlike cry

Can be due to translocation C5 -> C13 in parent. Offspring

inherits Ch5 with de. P arm

Disorders caused by structurally altered chromosome.

Certain Cancers: chronic myelogenous leukemia (CML), are

caused by translocations of chromosomes, karyotype 46 t(9.22)

Smaller than usual 22

Called Philadelphia chromosome

Causes cancers

Other gene not expressed or highly expressed can cause cancer,

and cause cell to divide rapidly.

The cells are the stem cells.

Many more of myeloid stem cells

So many of them are produced that basically less blood cells are

produced, less platelets (anemia, bleeding problems),

granulocytes (problem)

Some down syndrome can be inherited 14/21

How can trisomy 21 occur?


MOLECULAR BASIS OF INHERITANCE

Who discovered DNA?

Fredrich Miescher, isolated nucleic acid from WBC nucleic.

2 potential proteins, for material of inheritance, using pea plants,

drosophila etc.

Discovered from Bacteria

Frederick Griffith 1928 ~ discovery of the genetic role of DNA

began.

Worked with 2 strains of bacterium, pathogenic and one

harmless.

Strep and cocclic

Non-patho – patho were used in transformation – defined as a

change in genotype and phenotype due to assimilation of foreign

DNA

S cells: Smooth (killed mouse)

R cells: Rough (Healthy cells)

Something within cells was transformed substance of DNA

Worked on, similar, harmless bacteria to pathogenic bacteria.

Heat (kills S cells) – adds Heat cells to R (kills R cells) Swap over as vv.

Evidence that viral DNA can program cells:

Virus that infect bacteria

Such viruses, called bacteriophages (or phages), are widely used

in molecular genetics research.

Bacteria phase are great for taking a bacterial cell into dna

How to get a protein to a bacterial cell? Transcribed later into

protein.

Inheritance: Alfred Hershey and Martha Chase: Escherichia coli.

T2 infection

Protein capsid, new virus is made infection over and bye bye

Capsid stays outside the wall

Grew the viruses in presence of 2 radioactive isotopes, in 32P or

35S DNA

Infected the ecoli cells with either/or

If DNA then the radioactive DNA would be inside the cell

And the protein located outside the cell if it were transforming

factor.

And opposite if the other were used.

Erwin Chargoff: 1950: DNA is a material of inheritance

Still all gatc, different amounts of a and t’s and g and c’s

This became Chargaff’s rules

No” of A and T’s are equal

And no: of G and C’s

Soon after James Watson and Francis Crick published one page

paper in Nature

Structure of DNA: of Crystallography to study molecular structure

X ray crystallography = raised light to give structure of

molecules.

Able to deduce that DNA is a double helix

Backbone that is sugar phosphate backbone

And width etc

Then they build the model

At The Gold Coast

The primary structure of DNA has 2 major components:

A backbone made up of the sugar and phosphate groups of a

deoxyribonuleotides.

A series of nitrogen-containing bases that project from the

backbone

DNA has directionality

One end has an exposed hydroxyl group on the 3’ carbon of

deoxyribose, and the other end has an exposed phosphate group

on a 5’ carbon

The molecule thus has a 3’ end and a 5’ end

The strands line up in antiparallel strand creating a double helix

And there are hydrogen bonds 2 b/w A and T and G and C

3 ideas (hyp) of how new strands and pairings

Conservative replication: parent molecule is turning into a

complete parent and continuing to daughter

Semicoservative : daughter molecule = one old strand an one

new strand, and second strand, 2 made up of old and new, and 2

totally new.

Dispersive: Model, the first replication causes the daughter cells

to be old and new and the second is the same.

Meselson and Stahl: designed experiment to test hyp.

Grew E.Coli in heavy nitrogen (15N)

Moved from heavy N to Normal N

To see how gen of replication, how much the heavy vs normal in

DNA

They were interested in DENSITY of molecules

Helicase: unwinds the helix

Single stranded DNA binding proteins (SSBPs) help strands stay together

Elastic bad analogy: Twist plastic band, and get to middle and open it up,

at either end they begin to twist, which is what happens to DNA

Topoisomerase helps to keep DNA from coiling

DNA polymerase 3 requires a primer which consists of a few nucleotides

bonded to the template strand, b/c it provides a free 3’ hydroxyl (OH)

group that can combine with an incoming dNTP form a phosphodiester

bond

The enzyme’s product is called the “leading strand” or “continuous

strand”


PROTEIN SYNTHESIS

Key concepts:

Gene expression is the synthesis of proteins from gene

sequences

Genes specify proteins via the processes of transcription (from

RNA molecule) translation (DNA)

Eukaryotes modify RNA after transcription

Translation is the RNA directed synthesis of a DNA

See linking of more of a story, know what DNA is, what inheritance.

How cells divide, how genes are the recipe book for life.

Proteins are made with different cells and different tissues.

While we have same genome (except repro) cells are different, b/c of

differential gene expression (some turned on and some turned off)

Gene expression (turning on gene and producing protein), and protein

synthesis

Sequences of genotype (different alleles)

Transcribed to mRNA -> messenger RNA (to write)

DNA -> RNA (amino acid) -> translated (protein)

DNA: gene expression

2 processors involved, transcription and translation

RNA is used as a template

Messenger

Ribosomes: rough ER

Genes specify proteins via transcription and translation:

Relationship : Physician Archibald Garrod, first suggested that inherited

diseases, were caused from defect in enzyme.

Thought that there had to be some kind of anbolyic reaction

o Metabolic pathway

George Beadle and Edward Tatum: experiments, bread mold, ->

X-ray, to make mutant Bread moulds. Couldn’t survive on

minimal media (medium that contains glucose (energy) nitrogen

(proteins) electrolytes) they could produce anything else.

They were all arginine (amino acid) deficient, they could produce

own.

Hyp: of one gene one enzyme

Cells on left hand side that could grow in minimal median

The products of a gene expression:

Some proteins aren’t enzymes,

Central Dogma,

DNA codes for RNA which codes for Protein

DNA -> RNA -> Protein

Genotype, determines the proteins we produce

All RNA aren’t all mRNA’s and are not translated into protein

o Eg: tRNA’s and rRNA’s

Some viruses can be reversed. “Herpes”

When the infect someone, their genes can be inserted into host

genome.

Enzyme reverse transcriptase

DNA structure: revision

DNA is long chain (antiparallel) 3 prime end = 3 prime carbon on

sugar, hydroxyl end

5 prime end = 5 hydroxl

AT have 2 hydrogen bond

GC’s have 3 hydrogen bonds

RNA structure:

RNA is a similar has 3 main differences

RNA contains ribose sugar; DNA contains deoxyribose sugar

RNA contains the pyrimidine uracil (U) instead of thymine (U

pairs with A)

RNA is considered to be single stranded, whereas DNA is double

stranded (there are some RNA that have a fold in a double

stranded way)

During transcription, a DNA strand provides a template for the synthesis

of a complentary.

mRNA

Messenger RNA (mRNA) takes the message from the

chromosome to ribosome using the DNA template

3 nucleotides form one codon specifying one amino acid (start or

stop)

mRNA has 5’ to 3’ polarity or direction

Other RNA = ribosomal RNA

rRNA

Binds mRNA and tRNA on the ribosomes

rRNA consists of 2 parts that function together and small subunit

Ribosomes:

Have 3 binding sites:

P site

A site

E site

tRNA: has an anticodon (white) and is complimentary to codon in red

Not all proteins aren’t enzymes: they revised to 1 gene 1 protein.

Hemoglobin (each polypeptide has own gene)

Beadle and Tatum’s hyp:

tRNA

The mRNA message is translated into protein with the help of

transfer RNA (tRNA)

From amino acid, to ribosome – anticodon

Molecules of tRNA are not identical

Carries a specific amino acid on one end

Why can’t proteins ben translated directly from DNA?

DNA = well protected

Can have an RNA transcribed and make lots of proteins

Don’t want this happening at DNA level

Each RNA transcript can be translated repeatedly

Transcription:

Where DNA is used as template to form complementary mRNA

RNA synthesis is catalyzed by RNA polymerase, which unwinds

the DNA and adds the RNA nucleotides

Similarities to DNA synthesis (DNA copy so cell can replicate)

Genes producing their proteins

DNA unwound (RNA polymerase) polymer of RNA not DNA

Transcribes one template strand, makes one RNA molecule

Often called the coding strand, is almost identical to other coding

strand, however (T is changed with U)

Bacteria have a single type of RNA

o Eukaryotes have 3 RNA

o RNA polymerase 2 is used for mRNA

o Like the DNA polymerase performs a template-directed

synthesis

How does it know where to start, due to specific sequence called

“promoters” (like switcher with flag)

RNA polymerase is quite complex molecule, made up of a core

enzyme, also made up of a sigma subunit.

o Work with RNA polymerase

o Turn on

o Certain things are activated

Bacterial promoters: are called a (-10) box and a (-35) box.

Eukaryotes: a bit more complex, don’t have the similar boxes like

Prokaryotes

TATA box (centered about 30 base pairs)

Eukaryotes also have transcription factors are called basal

transcription, because they turn genes on

However there are some that Promoter that are more complex.

Prokaryotes have no nucleus segregating transcription from

translation and can transcribe and translate the same gene

simultaneously. The new protein quickly diffuses to its operating

site.

Intervening regions: Introns

Exons: are coding regions for final mRNA

Splicing: intervening sequences.

Primary – immature RNA, 1 intron, 1 exon

Nerves come together to make up spliceosome

(eukaryotes only)

Primary RNA transcripts are also processed by the addition of a 5’ cap and

a poly(A) tail

The 5’cap serves as a recognition signal for the translation machinery

Poly(A) tail extends the life of an mRNA by protecting it from degradation

-> In eukaryotes, you can have polyribosomes, to translate.

Translation:

Translating that message, from DNA to mRNA (amino acids)

Language called “genetic code” language of the 4 bases and

then the language of amino acids.

From bacteria, to universal

There are 20 amino acids (but only 4 in DNA()

How it is read, in “triplet code” called a codon, non overlapping,

and contain no gaps. In the coding region.

Eg: amino acids, back to mRNA, ggcc etc… and the uca is read as

serine.

During translation, the mRNA base in triplets

Must be correct reading frame. (correct groupings)

Correct amino acids are produced for that gene.

There are also codes for “start” and “Stop”

Wobble:

The genetic code is redundant, but not ambiguous – redundancy

is to do with the same amino acid, being coded by the same aa.

Not ambiguous, every single codon only codes for one amino

acid.

Genetic Code:

o Nearly universal, shared by the simplest bacteria to the

most complex animals

o Transcribed and translated after being transplanted from

one species to another

mRNA: directs amino acids sequence

tRNA: carries correct amino acid

rRNA + proteins = RIBOSOMES which have large and small subunits, E, P

and A sites

E: tRNA’s no longer bound to an amino acid “exit” the ribosome

P: Pepetide bond forms that adds an amino acid “peptidyl

transferase” using ATP and GTP. Made up of a chain of amino

acid in a peptide bond.

A: Accepter site for aminoacyl (AATS) tRNA

UCA: specifies Serine

Ribosome: large and small subunit, small sites for tRNA,

A site, tRNA is carrying an amino acid

o Initiation (1)

mRNA binds to a small ribosomal subunit, charged

tRNA (carrying methionine) attaches to the start

codon at the P site on the small subunit

Large site happens.

o Peptide bond (2)

Following on from last, Initiation complex, tRNA

carrying in P site, E site is empty

A new tRNA comes along and bonds to acceptor site

Complimentary to start site.

#2 a peptide bond forms between thyamine and

amino

#3 translocation (mRNA) moves along by one codon

o Termination (3)

o When everything stops, comes along and breaks

everything apart.

Translation, energy requirements:

4 P (phosphate) bonds are needed for the formation of one peptide bond:

2 P bonds during formation of aminoacyl tRNA

2P bonds from GTP during binding of aminoacyl

extra GTP for initiation complex termination

Translation Base- Pairing

mRNA – tRNA ((codon – anticodon)

mRNA and small ribosomal subunit

tRNA’s and ribosomal subunits at A and P sites

Proteins can be modified, by cell.

Sometimes they may be induced in an inactive state, then

activated.

Folding is involved

And often addition and removal of molecule can play a role.

Summary of Eukaryote:

DNA to Protein

Starting in nucleus

DNA double helix

Translated (gene turned on, RNA polymerase)

RNA polymerase catagorises symphases

Interons are removed

A capa is added

Move out through nuclear pores

tRNA’s come along

And produce a polypeptide

AATS (charging tRNA’s)

Amino acid around cytoplasm

Types of mutation:

2 main types of mutations caused by small changes in the DNA

sequence.

Substitution: one base is substituted for another

o One base replaced with another base

o Silent mutations- because of fact of 3rd base, in an amino

acid, there are 4x bases. There isn’t going to be much

difference.

o Missense mutation: when it codes for a different amino

acid. Might behave differently

o Nonsense mutations: an amino acid is changed from a stop

codon. Not always function

Exam: sickle cell disease (anaemia) has a specific

mutation for the 6th codon. Individual without

mutation.

Substitute (instead of ctc, cac). Causes the

haemoglobin molecule, made up of polypeptide to

fold differently. B/c it is important to RBC due to

carrying of oxygen, molecule isn’t working well.

Therefore causes the cell to have a sickled shape.

Insertion or deletion can cause a frame shift

mutation: way sequence is read. Read in 3 bases.

Change way sequence is read.

o

Inerstion or Deletion of base’s (indel)


GENE EXPRESSION AND REGULATION

Key Concepts:

Differential gene expression leads to different cell types in multicellular

organisms

Development in multicellular organisims results from cell devision, cell

differentiation and morphogenesis (cell can become a liver cell.

Bicoid: Drosophila in embryonic development. Model organisms

In regard to humans, all organisms in Eukaryote organisms share

similar genes.

Homeotic genes are master regulatory genes with homology in most

organisms, how if women are pregnant rectanyl acid (vitamin a) = toxic

due to expression pattern in homeotic genes.

Share across all organisms

Teratogens, agents that cause birth defects, things that have happened in

past and recommendations.

What happens in Embryonic development

Not much difference in cells

During development, morphogenesis happens, creates embryo with tail

etc

Cells, organize themselves to this form.

How this happens, a cascade in fully formed embryo that forms at birth

Fertilization, cleavage, cell division etc

Cell differentiation: cells are specialized in structure and function

Morphogenisis = shape in organsism

Differential gene expression results from genes bein regulated differently

in each cell type

A cytoplasm of egg contains molecules in RNA proteins, called cytoplasmic

determinants (determining what genes are going to be turned on or off

depending on concentration)

They are placed in the egg, during egg production

They are not zygotic, they occur from mother

Another that is involved, are not evenly distributed

As cells begin to divide, the signal to each other. To get

differences to happen.

This is called induction

What happens???

o Sperm: very little cytoplasm. Egg has large amounts of

cytoplasm and different molecules, round and triangle (not

evenly distributed)

o Sperm Meets Egg : zygote, begins to turn on genes

o At division : each of 2 cells are different

o First division : Early embryo (32 cells) signal to cells

above, in particular cells for different genes to be turned

on.

Before cells become differentiated, they become determined. (May not

look like a differentiated cell type)

Early cells, that are determed however not differentiated…

A pre curser skeletal muscle cells (cell type: CT) When they were

a embryonic cell (before specialized) have potential to become

an other cell type.

A nearby cell will signal, a cell type, to turn on a master regulatory gene

will (once turned on) will produce a protein= transcription factor (control

to turn on)

One particular is MyoD (gene) involved in pre-cursor cells, that has the

potential to turn into skeletal muscle. (transcription factor)

Depending of position: depends on signaling.

Morphogenesis: Pattern of form (drosophila) body plan.

Drosophila, has head to tail (axis)

Development from egg to lava: very early egg develop (follicle

cells and nurse cells [early mRNA and proteins] creating

differences during division)

Egg shell, eggs layed

Embryonic development

Embryo is segmented (morphogenesis has happened)

NB: lava, has a noticeable head and tail.

Gene expression:

Process in development

Maternal determinants: maternal effect genes (maternal mRNA’s)

Zygotic genes. Nomes of zygote

Cytoplasmic determinants are in a maternal effect genes

Establishing the basic stricter = head tail called “egg polarity

genes” or “coordinate genes”

Zygotic genes: turned on by maternal effect genes, once

fertilization occurs, proteins bind to genes of zygote.

Maternal effect genes:

Bicoid: is maternal effect gene, translated after fertilization;

allows first part of polarity to occur. Anterior end – posterior

concentration is less and less.

o High levels of transcription of the Anterior (head) of area.

Not turned on

o Embryos have a mutation, end up as a 2 tailed embryo.

Because bicoid cannot turn on genes to make anterior

parts, mutant larvae happens.

Maternal effect gene regulate zygotic genes: Genes of the zygote

2 main categroies

o The segmentation genes: they form the early segments

o Homeotic genes: give segments more identity, structure.

Fingers, toes etc

Look at cascade of gene expression, first lot are maternal effect

genes, at egg due to fertilization

o Turn on zygote genome

o Transcription factors that cause development

NB: Know hierarchy of genes

One particular gene is “sonic hedge hog”

Named after phenotype: general phenotype

***RUNT (gene) see what happens in humans HINT******

Segmentation gene: pair rule gene of drosophila

Mutations in gene, cause cleidocranial dysplasia

Lack of collar bone (malformed collarbone)

Problems with skull

Polytene chromosomes: giant chromosomes that happen in most flies,

happen in salivary glands- make multiple copies of chromosome but don’t

separate. Many copies of these gens increase transcription.

For all cells to start differentiating, because this is easy to see. Is that

regions of different, produce “puffs” will be at different regions of

chromosome.

When larvae molts shell, genes are expressed.

Homeotic genes; are involved in a more precise direction of different

segments

What happens if you receive a mutation in homeotic gene is

called “Homeosis”

This is when you have a duplex in development. (ie. When in

place of antenna there are legs)

Human: ACS: auriculocondylar syndrome, upper jaw and lower

jaw are same. Homeosis

Hox Genes:

Similar homeotic gene as flies

39 hox genes (human)

Common ancestor

Synpolodactyly

HoxD13: means there are a lot of PolyA tract

o Expansion mutates gene

MEOX1 : mutations, mesenchyme homeobox 1

Teratogens: Warfarin: sever deformities

Organogenic times (first trimester) is radioactive

Retionic acid: effective as acne treatment

Also called isocretinoin, roaccutaine retin A

Malformations: particularly in craniofacial.

NHMRC alcoholic recommendation during pregnancy since 2007 is 0%

intake.


DEVELOPMENTAL GENETICS


BIOTECHNOLOGY

Explain how advances in recombinant DNA technology have helped

scientists study genomes.

2. Describe the natural function of restriction enzymes and explain how

they are used in recombinant DNA technology.

3. Outline the procedures for cloning a gene in a bacterial cell.

4. Describe a cloning vector with an example.

5. Describe two techniques to introduce recombinant DNA into

eukaryotic cells.

6. Describe the Polymerase Chain Reaction and its application

7. Describe how DNA technology is used to study the sequence,

expression and function of genes

Describe how DNA technology can have medical applications in

such areas as the development of gene therapy, vaccine production,

and the development of pharmaceutical products.

9. Explain how DNA technology is used in the forensic sciences and to

determine paternity.

10. Describe how gene manipulation has practical applications for

environmental and agricultural work.

11. Describe reproductive and therapeutic cloning and why these

techniques are controversial.

12. Discuss the safety and ethical questions related to recombinant

DNA studies and the biotechnology industry.

13. Describe the different types of DNA sequence arrangements.

DFN: technology involving the combination of different types of DNA =

recomibinant DNA

Genetic engineering – manipulation of genes for practical purposes

Closing- Gene organisms

2 main goals for gene cloning:

Protein production: for research purposes, or may not, bulk

protein.

Eg insulin

Gene Transfer: Introduction of a foreign or manipulated gene into

a cell.

Useful for gene therapy, animal or plant improvement.

11/11/14 8:28 AM

2 organisms need to be able to create new species.

Post zygote of species (isolation)

Pre zygote (behavioural) Geographical, physical barriers

Allopatric speciation: 2 species become different

Like on 2 different sides of a river… warm/cold weather

Natural Selection: Charles Darwin

Species diverge

One species can diverge into 2

However are

Sympatric diverge

Artificial selection

Same species, can have fertile production

Dog breeding

Gene pool would be genetically isolated

Morula: - raspberry (latin)

Cells wad 32

Blastula: bilateral symmetry, built around a tube.

Gastulation

Begins when an indentation forms on blastula

Blastopore: indentation (creating hollow bead of cell)

Protostone:

Deuterostome: A butthole attached to a bunch of cells

At the moment (ectoderm (outer skin) (endoderm (inner)

digestive tract) Mesoderm (repro, etc))

Third layer of tissue,

Sea sponge doesn’t have a mouth and anus… Radial symmetry

85% genetically similar to mice

Developmental regulatory genes:

Hox genes: They are the planner

Genes and Diseases

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Transcript of Genes and Diseases