Genetics Flashcards
ploidy level
the number of chromosome sets that a cell carries Eg haploid 23, diploid 46
homogametic sex
individuals with two of the same sex chromosomes
heterogametic sex
individuals with two different sex chromosomes
somatic cells
all cells in the body of an organism apart form the sex cells (gametes)
germ cells
cells that give rise to gametes
meiosis type of division
reduction division (number of chromosomes becomes halved)
synapsis
when the maternal and paternal homologous pairs of chromosomes pair up
chiasma (chiasmata)
the point on the chromosome where crossing over occurs (the chromosome breaks)
recombinant chromatids/chromosomes
chromatids that have had crossing over occur to them (they have a new combination of alleles)
non-recombinant chromatids/chromosomes
chromatids that have not had crossing over occur to them 9have had no change in their alleles)
formula for number of possible chromosome pairs from independent assortment
2^n where n=the haploid number of the organism
when are chromosomes most visible
at metaphase
genotype
the set of alleles present in the DNA of an individual organism
homozygote
an individual with the homozygous genotype
heterozygote
an individual with the heterozygous genotype
Hemizygous
used to refer to males when talking about X-linked genes. Can be hemizygous dominant/recessive
phenotype
the physical representation of the genotype of an individual
complete dominance
where one allele is dominant over the other so the heterozygous individuals express the dominant trait only
incomplete dominance
when neither allele is dominant over the other so an intermediary or blended phenotype occurs in heterozygous individuals
codominance
when both alleles are equally expressed in the heterozygous individual therefore no phenotype of fully dominant
epigenetics
different environment causes methyl groups to attach to the cytosine bases of the DNA, however the DNA remains unchanged
environmental influencers
DNA is unchanged but the environment changes the way these genes are expressed Eg chemically
reprogramming
when epigenetic markers are erased during meiosis
genetic cross
the deliberate mating of two organisms to determine the inheritance pattern of particular traits
monohybrid cross
a cross following one trait in an organism (same gene at the same locus)
dihybrid cross
tracking two traits in an organism (tow different genes at two respective loci)
non-linked traits
traits that are inherited independently of one another as they are on separate chromosomes
linked genes
genes that are inherited together as they are found on the same chromosome, known as linkage.
HhKk + HhKk expected ration
9:3:3:1
HhKk + hhkk expected ratio
1:1:1:1
fixation
when an allele dominates a whole population
trisomy
when there is an extra copy of a chromosome
monosomy
when there is only one copy of a chromosome
down syndrome: abnormality
trisomy 21
down syndrome: symptoms
intellectual disability
developmental delays
Klinefelter syndrome: abnormality
two x chromosomes and one y
Klinefelter syndrome: symptoms
low testosterone
reduced male characteristics
Turner syndrome: abnormality
missing an X chromosome, have 1 X chromosome
Turner syndrome: Symptoms
short stature
infertile
triplets/codons
DNA is divided into sets of three nucleotide segments which code for amino acids that when join form a protein
aneuploidy
an abnormal haploid number of chromosomes
test cross
used to find an unknown genotype by crossing an individual with the dominant phenotype with a homozygous recessive individual. Type of monohybrid cross.
histone
proteins that the DNA wraps around
genome
all the genetic information in a haploid set of chromosomes this can also be used on a larger scale with reference. For example the genome of the cell or person
Nucleosome
8 histones wrapped in DNA
chromatin
multiple nucleosomes, which makes up Chromosomes
