Chapter 14 Flashcards
(35 cards)
What is a mutation?
-a heritable change in the genetic material
-passed on via meiosis of sperm and egg
occurs in S phase DNA replication or unprepared DNA damage.
What causes DNA damage?
radiation
reactive molecules produced in metabolism
chemicals in the environment.
What is the most common form of a mutation?
the substitution of one nucleotide pair for a different nucleotide pair, but still relatively rare, post mutations.
Why does RNA have a higher mutation rate than DNA?
RNA is a less stable molecule than DNA and the replication of RNA lacks a proofreading (backtracking) function.
What is the average substitution error number in a human?
about 1 nucleotide per 10 billion nucleotides replicated
Why do female gametes suffer less from replication derived mutations than male gametes do?
females are born with eggs already made where males are constantly producing sperm
Why are woman eggs “bad” as they get older?
when ovulation occurs the egg is in meiosis I and once the egg is fertilized it enters meiosis II, as a woman ages the mitotic spindle oxidizes causing problems with separation
What are germ and somatic cells?
germ cells: haploid gametes and diploid cells
somatic cells: non reproductive cell
is the rate of mutation per nucleotide greater in somatic or germ cells?
somatic cells.
why do humans have such a large rate of mutation per genome per generation?
humans have a large genome and undergo many cell divisions per generation
what is the number of nucleotide substitution mutations per genome in one generation?
30 or 60 per diploid zygote.
what percent of zygote mutations have come from the father and why?
80% because at 30 males have gone through 400 cycles of DNA replication and cell division before meiosis compared to woman who have only had 30.
Why can such a large number of mutations occur in humans?
a very small proportion of the genome is actually involved in regulating gene expression or coding for gene products
what to somatic mutations and germ mutations effect?
somatic- only the individual in which they occur
germ- transmitted to future generations since they occur in reproductive cells.
what mutation explains genetic diversity
germ line mutations
What factors give rise to cell growth and preventing cell growth?
promotes cell growth- proto-oncogenes, cyclin-CDK
tumor suppressor- p53, checkpoint proteins
how many mutations must occur before cancer?
3 successive mutations of the same cell.
What is a genetic risk factor?
A mutation that increases the risk of diseases in an individual. doesn’t make you have the disease but the likelihood of the disease happing increases
What are the major risk factors in
colon cancer
breast cancer
colon cancer- APC, Ras, and p53
Breast Cancer- BRCA1 and BRCA2 genes
What were the lederbergs trying to investigate with their experiment?
- mutations occur randomly in bacterial populations and over time become more common in the presence of an antibiotic
- the antibiotic (environment) induces or direct antibiotic resistance.
in what sense is a growth medium that contains an antibiotic selective?
because it selects for a particular attribute or element, in this case antibiotic resistant cells
in what sense is a growth that contains only nutrients, nothing toxic non-selective?
because all cells were able to grow and form colonies
what are point mutations?
changes in a single nucleotide.
How does DNA polymerase correct mistakes?
a proofreading function of DNA polymerase during replication, acts to remove an incorrect nucleotide from the 3’ end of the growing DNA strand.
