Genetics Exam 1 Vocab

epigentics

how environment causes changed in gene expression without altering DNA sequence (ex. methylation)

model organism

there are 6 (mouse, yeast, fruit fly…)

• short generation time, produce many progeny at a time, easy to rear in lab environment, can do controlled genetic crosses, numerous genetic variants, we know their DNA sequence

pangenesis

germ-plasm theory

preformationism

blending inheritance

prokaryotic cell replication vs. eukaryotic

cell theory

what are the following structures in chromsomes: telomere, centromere, microtubule, spindle fibers, kinetochore, chiasma

explain the steps of the cell cycle

steps of mitosis

steps of meiosis

cell cycle regulation proteins (2)

cohesin

oogenesis

plant meiosis

plant meiosis vs. human gamete production

locus

hemizygote

mendel’s pea experiment and what he found

probability, multiplication and addition rule

sry gene, why is Y small?

pseudoautosomal region

different chromosomal sex determining systems

haplodiploidy

environmental sex determination

fruit fly sex determination

neutral gonads

sex linked traits

dosage compensation

reciprocal cross

to see if a trait is sex linked, cross mom with trait to dad w/o trait and then do the opposite, then compare results.

trait

what form of a feature you have, determined by an allele

characteristic

a feature, determined by a gene. Depending on the allele for the gene, you can get different forms of a feature (trait)

gene

a section of DNA on a chromosome that determines a characteristic

allele

one of 2+ forms of a gene. Each allele has a different DNA sequence that determines a trait for a characteristic.

homologous chromosomes

a pair of chromosomes (1 or 2 DNA molecules each) that have the same genes but may have different alleles. One chromosome is from mom, one from dad.

only in 2n

sister chromatids are NOT homologous pairs

sister chromatids

identical copies of chromatids, created in S phase in cell cycle as a result of DNA replication.

independent assortment

if performing a dihybrid cross, the separation of A/a alleles will not impact the separation of B/b alleles. In a cross involving 2+ traits, alleles for each trait seperate independently

states that in meiosis I (specifically Anaphase), when homologous chromosomes separate, the they seperate independently of the others. This is how genetic diversity is created in meiosis (in addition to crossing over)

This only occurs in meiosis, since mitosis does not involve crossing over and alleles do not seperate randomly (since daughter cells and parent cell are all the same)

synapsis

the process of homologous chromosomes closely pairing, they connect via chiasmata (protein complexes)

tetrad

the closely associated four-sister chromatids of two homologous chromosomes

bivalent pair

a pair of homologous chromosomes

segregation

two alleles for each gene separate so each gamete gets only one allele for that gene.

particulate hypothesis

developed by Mendel, states that there are hereditary particle (now we know they are genes) in each parent that is passed down to offspring, and they do not blend.

monohybrid cross

a cross between two heterozygous individuals (for 1 allele)

test cross

done to find the genotype of a dominant phenotype individual (A_). Cross the individual with a recessive individual (aa). The phenotype of the offspring will tell you the genotype of the unknown parent.

genic sex-determining

a sex-determining system in some organisms (like protozoa or fungi) that do not have sex chromosomes, but rather genes that determine sex.

monoecious

an organism that has both male and female reproductive structures in the body (hermaphrodite)

diecious

an organism that has either male or female structures

hetergametic

having two different sex chromosomes

homogametic

having two of the same sex chromosomes

sequential hermaphroditism

the ability to change sexes based on the environment or social cues

klinefelter syndrome

1 or more extra x chromosome in males, normal genitals but often small tested and sterile. Possible breast development and mental impairment

turner syndrome

XO. Short, broad chest, webbed neck, underdeveloped secondary female sex characteristics, sterile

poly X syndrome

3 or more X’s. Normal female characteristics, bur worse mental impairment the more X’s there are. Some are sterile

androgen insensitivity

normal XY, but disrupted androgen receptors. Causes underdeveloped male internal sex characteristics and high testosterone. Externally appears female. Is X linked recessive

XYY syndrome

normal mental capacity but very tall

true hermaphroditism

a mosaic, with some body cells XX and some XY. They have both male and female gonads. Can be causes by a genetic/developmental error OR less commonly by a male and female twin fusing together in the womb to form one baby that has XX and XY cells. Can appear like a male or female, it varies.

isogamy

egg and sperm have the same size and shape, contribute equally to cellular content of zygote

anisogamy

sperm and egg are different in size and shape, egg is often much bigger and contributes almost 100% to cellular content of zygote.