genetics Flashcards
incomplete dominance
the heterozygote has an intermediate phenotype
co dominance
the heterozygote displays the result of both alleles
epistasis
one gene masks the expression of another
sex linkage
if a gene is on one of the sex chromosomes, the phenotype and a genotype ratios vary for males and females
dominant allele
if you have it, you have a parent who did
recessive alleles
can skip generations
sex linked
mostly seen in males, can skip generations
amniocentisis
14-20 weeks
small sample of amniotic fluid taken with a needle
fetal cells in the fluid are cultured
karyotype prepared
pro: can diagnose non disjunction disorders
con: small risk of miscarriage
chorionic villus sampling (cvs)
8-10 weeks
small sample of cells from placenta is extracted with a suction tube inserted through cervix –> can be cultured and karyotyped
pro: can diagnose non-disjunction disorders earlier than amniocentisis
con: small risk of miscarriage
trisomy 18
Edwards Syndrome
die within 1 year
organ abnormalities
small head/jaw
XXY
Klinefelter Syndrome
2n + 1
male
breast development and wide hips
learning disabilities
poor beard growth
infertile
monosomy
XO
2n-1
Turner Syndrome
female
no puberty
short stature
infertile
genotype
GG or gg or Gg
phenotype
purple or white flower
centromere
links a pair of sister chromatids (centre part of chromosome)
centriole
organelle near nucleus –> involved in development of spindle fibers
centrosome
facilitates organization of spindle fibers
chromosome
DNA molecule, made up of proteins and DNA organized into genes
chromatid
one of two identical halves of a chromosome that has been replicated
chromatin
mix of DNA + histones that form chromosomes –> packages long DNA to compact/dense structures
histone
protein found in chromatin, bind to DNA
nucleosome
segment of DNA wound around 8 histones
prophase
1st phase of mitosis where cells thicken and condense
metaphase
spindle captures all chromosomes and lines them up on opposite ends
anaphase
sister chromatids separate and pull towards opposite ends
telophase
cell is nearly done dividing and starts to re-establish normal structure
mitosis
4 stages of cell divisions
meiosis
mitosis for sex cells
sister chromatids
identical copies formed by DNA replication that are joined with centromere
crossing over
allows new combos of genes (alleles) even if they’re on same chromosomes
synapsis
pairing of homologous chromosomes