module 3 Flashcards
genome
- entire complete set of genetic material in a cell
Ploidy
- number of copies of the genome (n)
- can be haploid, diploid, triploid
- not static: vary throughout ones lifetime
Chromsomes
- composed to genetic material (DNA/RNA coiled around histones)
- can be circular or linear
Outline the 2 types of mutaions
- spontaneous: occurs without external cause - replication errors
- induced: by mutagens (radiation and chemical)
alleles
variant of genes caused by mutations and can be different lengths
Point mutations
change in a single nucleotide
Base substitution
1. silent: no effect
2. missense: changes the amino acid
3. nonsense: results in a stop codon
Base deletion or addition
1. frameshift: causes the reading frame to shift
Can mutations occur in non-coding reigons
Yes, even though they are not translated
- changes can affect timing, location or level or gene expression
difference between horizontal transmission and vertical transmission
horizontal occurs when genetic info is passed to a member of the same generation whereas vertical refers to the passing of info to the next generation
recombination
crossing over between chromosomes
can occur between sister chromatids in a chromosomes but doesnt result in genetic difference
What is aneuploidy and list 2 types
caused by non-disjunction
trisomy: 3 chromosomes (down syndrome)
monosomy: one chromosome
List the different mechanism of sex determination found in nature
- Environmental: incubation temp of reptilian eggs
- genetic: ploidy, ratio of autosomes to sex chromosomes
- sex determining gene
Heterogametic and homogametic
hetero = XY and homo = XX
Difference between non-disjunction at meiosis 1 and meiosis 2
at meiosis 1: homologous chromosomes fail to seperate
at meiosis 2: sister chromatids fail to seperate
Mendel’s first law
alleles always segreagate away from each other gametes
purpose of reciprocal cross
determine whether trait is sex-linked
is sex-linked when phenotypes of offspring are different when genotypes are swapped
mendel’s second law
independen assortment: alleles of seperate genes will always segregate independently into gametes
Why is recombination in linked gene less likely to occur
the closer loci are the lower the frequency of a recombination event
Test cross
cross to homozygous recessive individual test for linkage
back cross
cross between offspring and parent
incomplete dominance
one functional allele is not sufficient to generate wild-type phenotype
co-dominance
each allele is sufficient to generate a phenotype
monogenetic trait
trait controlled by one gene
polygenetic trait
trait controlled by more than one gene
genes can interact to build traits
Different transcription of genes
- constitutive: expressed under all conditions
- regulated: expressed under certain conditions
- positive control: increase/turning on transcription
- negative control:decrease/turning off transcription
