Chapter 3 Flashcards
(30 cards)
Diploid number
2n. total # of chromosomes. 46 in humans.
haploid number
n. n=23 in humans.
mitosis
cell division produces many cells, creates two daughter cells.
G1
waiting for signal to divide. gene expression.
s phase
dna replication. creates two identical sister chromatids.
g2
prepares for division
mitosis stages
prophase prometaphase metaphase anaphase and telophase(and cytokinesis)
centromere
dot where sister chromatids meet
chromosome
structure that has a centromere
What event reduces the amount of DNA by one-half during meiosis I?
The separation of homologous chromosomes
What event reduces DNA amount by an additional one-half in meiosis II?
sister chromatid separation
wild type
most common in population
hemizygous
males. only one chromosome is present. guy can only be big A or little a in XY.
X linked recessive
X^wX^w or X^wY. affected grandfather passes to carrier daughter (skips female) to affected grandson
x linked dominant
X^w+ X^w or W^w+ Y fathers would pass it on to all daughters.
autosomal dominant
everyone who has it has to have an affected parent.
autosomal recessive
affected offspring; unaffected parents. can affect male or female.
y linked
fathers to sons to sons to sons…
if the question says “theyre about to have a girl”
dont take that into account 1/2 cuz they already told you that. if they dont tell you the gender of the child, take into account 1/2.
Crossing over usually occurs during:
prophase of meiosis I.
Below is shown the order of genes along a given chromosome. An individual homogygous for mutations in gene A and gene E (i.e.- aaee) is crossed to an individual homozygous for a mutation in gene D (i.e.- dd). Assume all other alleles are wild-type (big letter). In the F1, if a single crossover event occurs during meiosis between the D and E genes……..
ONLY one changes on the line. last letter switches for both.
Ignoring recombination, how many different types of gametes can be produced from an organism with a diploid number of 6 chromosomes?
2n=6. n=3. so it is 2^3= 8. (bc two possible orientations)
What characteristic would you NOT expect to see in a pedigree that outlines an X-linked recessive trait?
The trait is commonly passed from fathers to sons. cant pass X from father to son, only Y.
Red-green colorblindness is caused by an X-linked recessive mutation. For a red-green colorblind male, which of his grandparents may have been the source of his colorblind allele?
either of his mom’s parents. He had to get his X from his mother, and she got an X from each of her parents. So either of his maternal grandparents could have had the allele.
