GENETICS Flashcards
what does the word genotype mean
genetic material passed to offspring
what is a phenotype
observable traits of individual
what is the chromsome code for a female
xx
what is the chromosome code for a male
xy
how many pairs of chromosomes do humans have
23, half from mother half from father
what are dichotomy traits
traits in one form or another but never in combination
define allele
two genes that control the same trait
define homozygous
IDENTICAL genes for same trait
define heterozygous
different genes for same trait
what cell division occurs for gametes?
meiosis
what is meiosis? how many chromosomes does each gamete have?
chromosomes half, each gamete would have half the number of chromosomes each
state the process of mitosis
chromosomes replicate and 4 daughter cells would be produced
what does DNA mean
deoxyribose nucleic acid
how many base pairs does DNA have and what are they
4, adenine and thymine, cytosine and guanine
where does crossing over occur?
chiasma
what does crossing over do?
form recombinant chromatids
what is rna
ribonucleic acid
which nucleotide base is replaced in RNA
thymine is replaced with uracil
what is a 3 collective nucleotide known as
codon
what is trisomy chromosome 21
extra chromosome on 21st chromosome
what does the gene dosage effect mean
150% genes - 150% MRNA 150% proteins
what does RNA do
complimentary copy of one strand of DNA molecule
what is PKU
single mutation of one gene
what does PKU cause
result in brain damage and caused by autosomal recessive gene
who does PKU occur in?
only affect homozygous individuals
what did mendel study
pea plants
what is the square called that helps to outline inheritance probability
punit square
what is meant by the term true breeding lines
interbred members produce same offspring with same trait
what is dna made of
make proteins of long amino acids
define heritability
how much variance of a characteristic within a population is due to hereditary
what are mz twins and how much CR do they share
identical twins and 100%
what are dz twins and how much CR do they share
fraternal twins and 50%
what is the effect of a more similar environment on hereditary?
increased estimate of heritability
what is the CR for mz and dz twins for depression
mz - 60% and dz - 15%
how is heritability calculated
compare correlation coefficents of either identical or non identical twins for the same trait
what does the weinberger approach suggest
heritability is a problematic construct
what does zhang et al 2015 findings show
mutant form of trytophan gene can result in many mental health problems
what does the example 1 of the gene for trytophan suggest
cells with the trytophan gene have 80% less seretonin than normal genes
what are the figures of zhang et als study
87 depressed pp - 9 had mutant gene
219 control - 3 had mutant gene
what does the example for gene with seretonin transporter show?
short form of seretonin transporter gene: brain over respond to emotions
is there a higher or lower brain activation for the short gene
higher brain activation in short gene for negative emotions
what is the amygdala do
responsible for emotions and memory
what does the diathesis stress model show
people with a risk factor gene who are exposed to stress have a higher likelihood of obtaining a disorder
what happens when genes interact with the environment
gene interact with the environment - can produce depressive symptoms
what does brown 1993 study show
depressed pp - 84%
control 32%
shows levels of stress experienced in previous year
what effect does stress have on depression
higher stress = higher chance of depression
does dna replicate
essential for dna to replicate
what occurs to heritability in a persons lifetime
increased linearity from childhood to adulthood
what is the link between environment and heritability
increased similar environment - increased estimate of heritability
where can PKU be detected
urine
what values is heritability measured on
0-1
