gn exam 2

what is important for gender assignment in older individuals?

chromosome analysis

hormone levels

internal anatomy

psychological identity

when is the tertiary sex ratio measured and what is its value?

later in life (any time after birth)

ratio more even at age 20: 100 to 100

after 20, female rates go up

example of penetrance

genotype for polydactyly do not show the trait

how does template slippage increase trinucleotide repeats?

during DNA replication, the new strand mispairs and loops out, causing extra repeats to be added

seen in: Huntingtons disease and fragile-x syndrome

what is the secondary sex ratio measured and what is its value?

at birth

male ration goes down: m105 f100

when is the primary sex ratio measured and what is its value?

at fertilization (xx vs xy zygotes)

approximate ratio 1:1 (theoretically)

more expected 120:100

what are examples of extensions to Mendel’s law?

incomplete dominance

codominance

multiple alleles

epistasis

polygenic inheritance

linkage

congenital adrenal hyperplasia

xx individual

excess androgen production

masculinized external genitalia

barr bodies: 1

usually raised female

what is penetrance?

the proportiojn of individuals with a genotype who actually express the phenotype

sex-linked inheritance

trait located on the x or y chromosome

Mendel’s law of random segregation

2 alleles for a gene seperate during gamete formation, so each gamete only recieves one allele

Mendel’s law of independent assortment

alleles of different genes assort independently into gametes

most common CF mutation in Ashkenazi Jewish Population

nonsense mutation

most common mutation in CF

CFTR gene, chromosome 7

1 in _ pregnancies spontaneously miscarry

15%

1 in _ live births have a chromosome disorder

150

double monosomy

missing one copy of 2 different chromosomes

what is reciprocal translocation?

exchange of chromosome segments between 2 chromosomes

what is roberstsonian translocation?

the fusion of 2 acrocentric chromosomes

what is anticipation?

disease appears earlier and more severe in successive generations

what is a nonsense mutation?

mutation that creates a premature stop codon, producing a shortened protein

what is a missense?

DNA chnage that alters one amino acid in the protein

autopolyploidy

multiple chromosome sets from the same species

how do polyploids arise?

failure of meiotic division

fertilization by diploid gametes

chromosome doubling after hybridization

chromosomal basis of turner syndrome

monosomy x (45,x)

monosomy

missing one chromosome (2n-1)

nullisomy

loss of both copies of one chromosome

lethal in humans

amphidiploids

allopolyploids that behave like diploids because chromosomes pair properly

polyploidy

more than 2 complete sets of chromosomes

Burkitts lymphoma is caused by…

reciprocal translocation (chromosomes 8 and 14)

triploid amnd tetraploid

3n and 4n

trisomy

one extra chromosome (2n+1)

chromosomal basis of klinefelter syndrome

47, XXY

double trisomy

extra copies of 2 different chromosomes (2n + 1 + 1)

tetrasomy

f0our copies of 1 chromosome (2n + 2 of same chromosome)

allopolyploidy

chromosome sets from different species

aneuploidy

abnormal number of chromosomes due to gain or loss of 1 or more chromosomes

double monosomy

missing one copy of 2 different chromosomes (2n - 1 - 1)

what is translocation?

movement of a chromosome segment to another chromosome