Post on 07-Jul-2018
8/19/2019 NMAT Review Biochem, Genetics and Central Dogma
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Prepared by Joshua Evans M. Bajao
National Medical
Admission Test (NMAT)
review:
Biology
Biochemistry
Macromolecules
! Simply put, a very large molecule that is
necessary for life.
! Created by the polymerization of smaller
subunits called monomers.
! 4 Types of the most important Macromolecules
Lipids Nucleic Acids
Carbohydrates Proteins
Macromolecules: Lipids
! A group of naturally occurring non-polar
molecules that contain hydrocarbons.
! Glycerol and fatty acids are the monomers of
lipids.
fatty acid
glycerol
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Macromolecules: Lipids
! Main function of lipids include energy storage,
signaling, and structural components of the cell
memrabe (Phospholipids).
! One of the main types of nutrients.
! Monosaccharides is the monomer of
carbohydrates.
! Polysaccharides may serve as a storage for
energy and or structural components.
! Includes sugars, starch, cellulose, etc.
Macromolecules: Carbohydrates
! Three of the most common disaccharides
Macromolecules: Carbohydrates
! Are large biomolecules that perform a vast array of
functions within the organism.
! Composed of one or more chains of amino acid
residues, the monomer for proteins.! The structure of an amino acid
consist of one carbon with
a carboxylic acid and an
amine group
Macromolecules: Proteins
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Macromolecules: Proteins
! Are Macromolecules composed by nucleotides.
! Nucleotides consist of a nitrogenous bases
(Adenine, Thymine, Guanine, Cytosine), a five-
carbon sugar backbone
(deoxyribose for DNA,
ribose for RNA), and a
phosphate group.
Macromolecules: Nucleic acids
CELLS Cell
! Cell is the smallest, most basic structural,
functional, and biological unit of life.
! Every organism is compose of one
(unicellular organims) or more (multicellular
organism) cell.
! It is the smallest unit of life capable of
replicating/reproducing itself independently.
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Cell Theory
! The cell is the most basic unit of life.
! All living organisms are composed of one or
more cells.
! All cells arise from pre-existing, living cells,
Matthias Schleiden and Theodore Schwann
Two types of Cells
Prokaryote Eukaryote
The main difference is that eukaryotic cell
have membrane bound organelles.
Prokaryote Anatomy Eukaryote Anatomy
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Summary:Difference between Eukaryote and Prokaryote
Prokaryote Eukaryote
Size ~0 .2-2µm ~ 10-100µm
Location of genomic material
(DNA)
Nucleoid region Membrane bound nucleus
DNA Single, Circular, lackhistones
More than one, linear, withhistones (protein)
Membrane bound organelles Absent Present
RNA/protein synthesis RNA and proteins:
Cytoplasm
RNA: Nucleus (nucleolus)
Protein: Cytoplasm (free
ribosome/RER)
:
:
:
:
Summary:Difference between Eukaryote and Prokaryote
Prokaryote Eukaryote
Motility Rotating Flagella (some) Undulating Flagella, Cilia
(microtubule arranged in a
9+2 manner), and orPseudopodia
Flagella Some (made of flagellin) some (made of microtubule)
Cilia Absent Some (made of microtubule)
Fimbrae and Pili Some Absent
Cell Wall Most, made of peptidoglycan Most, cellulose for plants,
chitin for fungi
-
Cell Cycle Mitosis
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Mitosis Meiosis I
Meiosis II Meiosis II: detailed
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Meiosis II: detailed
Genetics
Genetics
! Is the study of genes, heredity and genetic
variations among species.
! Gregor Johann Mendel, a scientist and an
Augustinian friar, is said to be
the father of modern genetics
due to his studies regarding the
pea plants.
Genetic terms
Gene – a stretch of DNA that determines a certain trait.
ex: Eye Color, Skin color
Allele – a specific variation of a gene.
ex: Blue eyes, green eyes, black skin, white skin
Dominant alleles – are alleles that show their effect even if the
individual has only one copy of the said allele.
Recessive alleles – are alleles that show their effect only if the
individual has two copies of the said allele.
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Genetic terms
Homozygous – a genetic condition where an individual inherits
the same alleles for a particular gene from both parents.
ex: AA, TT, yy, gg
Heterozygous – a genetic condition where an individual
inherits two different alleles of a particular gene from
both parents.
ex: Aa, Tt, Yy, Gg
Genotype – the organism’s genetic makeup
Phenotype – the organism’s observable characteristic or trait
Mendelian Inheritance (Laws)
Law Definition
Law of Segregation During gamete formation, the allele of each gene
segregate from each other so that each gametes
carries only one copy of the said gene
Law of Independent
Assortment
Genes for different trait segregate independently
from each other during gamete formation
Law of Dominance Some alleles are dominant while other are
recessive. An organism with atleast one dominant
allele will display the phenotype of the sa id allele
Mendelian Inheritance Mendelian Inheritance
If a pure bred yellow seeded pea plant was
crossed with another pea plant with a green
seeds:
a)
What is the genotypic ratio of the F2generation?
b) What is the phenotypic ration of the F2
generation
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Mendelian Inheritance
YY yyX
Gametes produced: Y Y X y y
Punnett square Y Y
y Yy Yy
y Yy Yy
Yy Yy Yy Yy
Mendelian Inheritance
Yy YyX
Gametes produced: Y y X Y y
YY Yy Yy yy
Punnett square Y y
Y YY Yy
y Yy yy
a) Genotypic ratio is 1YY:2Yy:1yyb) Phenotypic ration: 3 Yellow: 1 Green
Mendelian Inheritance
If a round yellow seeded pea plan that is
heterozygous on both traits were crossed to a pea
plant with the same genotype:
a)
What is the chance that the offspring will havea green seed that is wrinkled?
b) What is the chance that the offspring will have
a yellow seed that is wrinkled?
Yellow (Y) is dominant over green and round (R)
is dominant over wrinkled.
Mendelian Inheritance
YyRr x YyRr
YR Yr yR yr x YR Yr yR yr
YR Yr yR yr
YR YYRR YYRr YyRR YyRr
Yr YYRr YYrr YyRr Yyrr
yR YyRR YyRr yyRR yyRr
yr YyRr Yyrr yyRr yyrr
*Bold letter signifies the round phenotype
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Mendelian Inheritance
YyRr x YyRr
YY Yy Yy yy : RR Rr Rr rr
YY =!; Yy = 2/4; yy =!: RR = !; Rr = 2/4; rr = !
a) Green seed that is wrinkled = yyrr
yyrr = !(yy) x!(rr) = 1/16
b) Yellow seed that is wrinkled = Y_rr
Y_ = YY + Yy =! + 2/4 ="
Y_rr = "(Y_) x ! (rr) = 3/16
Mendelian Inheritance
Two pea plants were crossed, there genotypes are
as follows: TtRRYy and ttRrYy (T= tall i s
dominant to short; R= rounded seed is dominant to
wrinkled; Y= yellow seed is dominant to green).
a) What fraction of the progeny will be tall, and
has a yellow wrinkled seed?
b) What about short with green round seed?
Non-Mendelian Inheritance
Sometimes called as Neo-mendelian, is any
pattern of inheritance that doesn’t confirm to
Mendel’s law of inheritance.
Examples of Non-Mendelian Inheritance
Incomplete dominance
Codominance
Multiple allele
Sex-linked
Incomplete dominance
A type of dominance that occur when the
phenotype of the heterozygous is distinct, or
often an intermediate, to phenotype of both
homozygous alleles.
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Codominance
A type of dominance that occur when both
alleles are expressed equally and is visible as a
phenotype.
Multiple allele
A type of non-Mendelian
inheritance pattern that
involves more than just
the typical two alleles
that usually code for a
certain phenotype in a
species.
Multiple allele
! Cross between AaBbCc x aaBbCC.
What is the chance that the offspring are
light colored?
"
Aa aa; BB Bb Bb bb; CC Cc
" Aa – !(Aa) x "(bb) x !(Cc) = 1/16
" aa – CC – !(aa) x "(bb) x !(CC) = 1/16
Cc – !(aa) x 2/4(Bb) x !(Cc) = 2/16
Light colored = 1/16 + 1/16 + 2/16 = 4/16 = "
Sex-linked gene
! These are genes, thus, also the allele, that
are found in the X chromosomes alone.
! The result is that the females will have two
copies of the sex-linked gene while maleswill only have one copy of the gene.
! Females that have a heterozygous allele of
a recessive trait in their genotype are calledCarriers.
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Sex-linked gene (example)
Red-green color blindness is a recessive
X-linked gene abnormality. Suppose a normal
female carrier (XCXc) has married a normal
male (XCY).
a) What is the Genotypic ratio of their
offspring.
b) What is the Phenotypic ratio of their
offspring.
XCXc x XCY
XCXC XCY XcXC XcY
a) 1 normal female: 1carrier female: 1
normal male: 1 color blind male
b) 2 normal female: 1 normal male: 1 color
blind male
Sex-linked gene (example)
Central Dogma
of MolecularBiology
Central Dogma of Molecular Biology
Replication process of producing two identicalDNA from one original DNA template
TranscriptionProcess of copying the DNA templateinto an RNA
TranslationTranslating the RNA code into a proteinsequence
DNA
RNA
Protein
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Replication
Enzymes Function
TopoIsomerase Relaxes the DNA from its super-coi led nature
Helicase Unwinds the DNA helix at the replication fork
Single Strand Binding(SSB) protein
Bind to ssDNA (single stranded DNA) to prevent itfrom re-annealing (binding) after DNA helicase
unwinds it
DNA primase Provides a starting point of RNA (or DNA) for DNApolymerase to begin synthesis of the new DNA strand
DNA polymerase Builds a new DNA strand by adding nucleotides in a5’ to 3’ direction. Also performs proof reading and
Replication
Replication
Always remember, both strand of DNA double
helix complements each other
Purines A = T Pyrimidines
G = C
5’ ATG GAG CCA GCA TCG GAT TAA 3’
3’ TAC CTC GGT CGT AGC CTA ATT 5’
Thus, A + G = T + C
Transcription
Note: RNA polymerase doesn’t need a primer to propagate
Only one strand is transcribed (template strand)
Need a promoter region
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Transcription Transcription
Always remember, like DNA, RNA complements thetemplate DNA, with one exemption: Thymine is
absent in RNA. Instead, Uracil (U) complements
Adenosine (A).
DNA template
5’ ATG GAG CCA GCA TCG GAT TAA 3’
3’ UAC CUC GGU CGU AGC CUA AUU 5’
RNA
Translation
! Translation occur in the ribosomes
! There are three kinds of RNAresponsible for translation
"
mRNA – (messenger RNA) RNA that istranscribed
" tRNA – (transfer RNA)RNA that holds theamino acid
" rRNA – (ribosomal RNA) One of theconstituents of ribosomes, together withvarious proteins.
Translation – coding
5’ AUG GAG CCA GCA UCG GAU UAA 3’
Met Glu Pro Ala Ser Asp stop
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Translation Translation