Cancer & Mutations Powerpoint

SB2. Students will analyze how biological traits are passed on to successive

generations.d. Describe the relationships between changes in DNA and

potential appearance of new traits including• Alterations during replication.

InsertionsDeletionsSubstitutions

• Mutagenic factors that can alter DNA.High energy radiation (x-rays and

ultraviolet)Chemical

Kinds of cancer• Carcinomas – grow in the skin and he tissues that line the

organs of the body – Ex. lung and breast cancer

• Sarcomas – grow in bone and muscle tissue• Lymphomas – solid tumors that grow in the tissues that form

blood cells– Ex. leukemia, the uncontrolled production of white blood cells

•Cancer - Uncontrolled cell growth*Cells only grow

during the correct conditions*Limited by space, nutrients, chemicals, etc.

What is Cancer?

Tumor• Tumor - mass of cell due to uncontrolled

cell growth– Benign - an abnormal, non-threatening cell

mass– Malignant - uncontrolled cell mass that

continually divides and multiplies– Metastasis - spread of cancer cells beyond

original site

Cancer• Cancer cells, unlike normal

cells, continually grow even when the region is over crowded. – The cell does not recognize

the message to stop dividing.

• Normal cells will not go through cell division unless they are attached to neighboring cells. – The cancer cells continue to

grow and this leads to the spread of the problem throughout the body, also called metastasis.

What causes cancer?

•Growth factors - proteins that ensure the events of the cell cycle progress in proper order. •Ex Cyclins and CDKs

•Mutations in these proteins result in uncontrolled cell growth.

Cancer causes• Carcinogens - any substance that

increases the risk of cancer– Ex. Tobacco, asbestos, and radiation such

as X-ray, and UV light from sun.

Genes related to cancer

• Oncogenes – gene that causes cancer or other uncontrolled cell proliferation

• Proto-Oncogenes – gene that codes for proteins involved in the cell cycle

• Tumor-suppressor genes – code for proteins that prevent the uncontrolled rate of cell division

Discussion

Can Cancer Occur Organisms other than humans?

A. Yes

B. No

What is a mutation?

• Mutation – a change in the DNA of an organism• Germ-line mutation – occur in gametes of

organism– Passed on to offspring, do not affect the organism

• Somatic mutation – mutations in the organism’s body– Affect the organism, but not passed on to offspring– Ex. Skin cancer, leukemia, any cancer

What causes mutations?• Mutagens – agent that causes

mutations to occur within a cell. – Ex. Ionizing radiation, Base

analogs, Intercalating agents, and Bromine

Types of mutations• Chromosome mutations – changes in the

structure of a chromosome or loss of an entire chromosome.– Deletion – loss of piece of DNA due to

chromosomal breakage– Duplication – Chromosomes steal part of homologs

and have both alleles for each gene involved– Inversion – piece of DNA breaks off and reattaches

itself in opposite direction– Translocation – chromosome breaks off and

reattaches to a non-homologous chromosome– Nondisjunction – chromosome does not properly

separate from its homolog during meiosis

Chromosome Mutations

Nondisjunction

• Results in gametes receiving to many or too few chromosomes

• Ex. Down Syndrome = trisomy of chromosome 21

What kind of chromosomal mutation is this?

Original chromosome

A. Duplication

B. Translocation

C. Inversion

D. Deletion

What kind of chromosomal mutation is this?

Original chromosome

A. Duplication

B. Translocation

C. Inversion

D. Deletion

Gene Mutations

• May involve a large section of DNA or a single nucleotide within a codon

• Point mutation – the substitution or change of a single nucleotide

• Insertion or Deletion – one nucleotide is removed from or added to a sequence

• Frame shift mutation – occurs when codons are incorrectly grouped

Point Mutation• Can result in

– No effect - the protein structure is not changed

– Missense – one amino acid is replaced by another

– Nonsense – prematurely stop codon in amino acid sequence

Point mutation

• Ex. Sickle cell anemia –mutation in a single nucleotide that causes the malformation of the hemoglobin molecule which carries oxygen to our cells

Insertion and Deletion

The removal or addition of a nucleotide base to a sequence usually results in a frameshift mutation.

Using the genetic code provided, which chain of amino acids corresponds to this mRNA sequence?

UCAAUGGUCUGA

A. Glu, Tyr, Met, Arg

B. Ser, Val, Arg, Stop

C. Ser, Met, Val, Stop

D. Val, Iso, Asp, Stop

What if the first G was changed to a C, what would the new amino acid chain be?

UCAAUGGUCUGA

A. Glu, Tyr, Met, Arg

B. Ser, Leu, Arg, Stop

C. Val, Ile, Ser, Stop

D. Ser, Iso, Val, Stop

What affect does this mutation have on the function of the

protein?

• Proteins are folded in a specific fashion according to the amino acid sequence it contains.

• This would cause the function of the protein to be severely reduced or not functional at all.

Mutations lead to Evolution• Mutations are not always bad, they often

provide variations on proteins and sometimes these are advantageous to us.

• Survival of the fittest and Natural selection.

How can one tell the history of hereditary traits in his or her family?

• Pedigree – diagram of genetic history of an individual showing how traits are inherited over several generations

Pedigrees

• Genetic disorders – diseases or debilitating conditions that have a genetic basis– Carriers – individuals with one copy of a recessive autosomal allele;

do not usually express the disorder but can pass on to offspring

Dominant disorders Recessive disorders

Polydactyly

• Dominant trait that results in offspring with extra fingers or toes.

Hemophilia

A sex-linked, recessive genetic disorder that affects the individuals ability to clot blood.