Final Review Flashcards
what is genetics
the science of heredity and study of how traits and diseases are passed from one generation to the next
what are genes?
Chromosomes?
homologous pairs?
genes: physical unit of heredity
chromosomes: long molecules of double stranded DNA which contains genes
homologous pairs: chromosomes that carry genes for the same traits
types of chromosomes and what they mean
metacentric-centromere in the middle
submetacentric-centromere slightly off center
acrocentric-centromere close to end
telocentric-centromere at the end(no P arm)
3 essential components of nucleotides
Nitrogenous base
pentose sugar
phosphate group
replicate vs reciprocal vs test crosses
Replicate: repeating the same cross several times
Reciprocal: crossing the same genotypes but reversing the sex of the parents
Test: crosses to determine unknown genotype
ideal phenotypic ratio of F2 generation in a dihybrid cross? what happens to the ratio for a test cross of a heterozygous individual?
Standard Cross- 9:3:3:1
Test Cross: 1:1:1:1
what separates in meiosis I? meiosis II?
meiosis I: tetrads separate
meiosis II: sister chromatids separate
what keeps sister chromatids together during mitosis and meiosis
cohesin
stages of prophase I
leptonema
zygonema
pachynema
diplonema
diakinesis
what happens in pachynema and diplonema
crossing over
sex linked vs sex limited vs six influenced
Linked: traits determined by genes located on gametes
Limited: expression of phenotype is absolutely limited to one sex
Influenced: phenotype is influenced by sex, but not limited to one
when does oogenesis arrest
diplonema
what is chromosomal nondisjunction?
how does it affect ploidity?
it is failure of chromosomes to properly separate during cell division.
it can lead to abnormal chromosome numbers
main categories of structural aberrations that can occur in mammalian chromosomes
Deletion
Deletion and Duplication
Inversion
Translocation
what does acentric mean?
how does it occur after chromosomal break and terminal deletion?
acentric means the chromosome lacks a centromere.
it occurs when a part of the chromosome arm breaks off
2 types of inversion and their consequences
parAcentric: centromere outside inverted region
parIcentiric: centromere inside inverted region
what inversion type leads to tobiano coat color in horses
parAcentric
what is a deletion, what are its consequences
deletions are loss of a part of one chromosome arm
-small deletions have little/no phenotypic effects
-multigenic deletions cause loss of genetic material that can affect phenotype
2 main types of translocation
nonreciprocal: a piece of one chromosome is translocated to a non homolog and their is no reciprocal event
reciprocal: pieces of 2 non homologs switch places
what is the Philadelphia chromosome?
What is its homolog in dogs?
Philadelphia chromosome is caused by a reciprocal translocation
-Raleigh chromosome in dogs
what are extensions of mendelian inheritance
linkages that lead to unequal segregation and non independent assortment
genotypic and phenotypic ratio for incomplete and co-dominance
1:2:1 for all
6 modification on the 9:3:3:1 ratio
complementary
duplicate
dominant
recessive epistasis
dominant epistasis
dominant supression
what does complementary analysis distinguish?
it distinguishes mutations in the same gene from mutations in different genes
penetrance vs expressivity
Penetrance: probability of a gene being expressed
Expressivity: variability in presentation of the phenotype in penetrant individuals
complimentary gene modification
-phenotypic ratio
-what it is
9:7
flows through a pathway, both dominant alleles create wild type, absence of one or both dominant alleles leads to mutant phenotype
dominant gene interaction
-phenotypic ratio
-what it is
-9:6:1
-homozygous dominant produces one phenotype
-heterozygous produces a second phenotype
-homozygous recessive produces a third
recessive epistasis
-phenotypic ratio
-what it is
-9:3:4
-a recessive allele at one locus will mask the phenotypic expression of the allele at a second locus(EX. lab coat colors)
dominant epistasis
-phenotypic ratio
-what it is
-12:3:1
-dominant allele at one locus masks phenotypic expression of the allele at a second location(EX> summer squash color)
dominant suppression
-phenotypic ratio
-what it is
-13:3
-dominant suppressor at locus 1 can mask dominant allele at locus 2
T/F a 2 point linkage map is the most effective way to build genetic maps
FALSE. 3-point is more effective
what is the transforming agent for bacterial transformation?
DNA
what is the most significant nucleoside phosphate?
NTP(precursor to ATP)
5 types of DNA polymerase and their properties
Pol I: remove primer and fill gaps
Pol II: repair DNA damage and replication fork
Pol II: proofreading
Pol IV and V: repair DNA damage
what is RNA priming
universal feature of initiation of DNA replication
steps of DNA replication
-unwind and stabilize DNA helix
-initiation of DNA synthesis, synthesis of RNA primers
-DNA synthesis
-proofreading and error correction
where does transcription occur in the cell
in the nucleus
what is needed to make the RNA ploymerase holoenzyme
sigma subunit
how many different types of RNA polymerase are there for bacteria
ONE
inverted repeats vs rut sites
Inverted: form hair pin loop followed by series of U’s to slow RNA polymerase
Rut-site: Rho protein binding to form termination sequence and release RNA polymerase
3 types of RNA pol and what they transcribe for
Pol I: rRNA
Pol II: mRNA
Pol III: tRNA
3 eukaryotic promoter consensus sequences
TATA box
CAAT box
GC rich box
2 prokaryotic promoter consensus sequences
pribnow box
-35 sequence
3 types of post-translational processing?
what moves into the cytosol after?
5’ capping
3’ polyadenylation
intron splicing
mature mRNA enters cytosol
where does translation occur in the cell
cytosol
steps of translation
-ribosome of large and small subunit hold mRNA to dock it
-incoming tRNA is charged and carries AA to A site
-tRNA aligns anticodons with mRNA codons and moves to P site
-AA attached to polypeptide
-tRNA exits at E site no longer chraged
main function of small and large ribosomal subunit
facilitate translation
function of P. A, and E sites in translation
P: holds tRNA which polypeptide is attached
A: binds new tRNA containing an AA to be added to the polypeptide
E: exit site for tRNA
3 phases of translation
initiation
elongation
termination
main components of translation in eukaryotes
eukaryotic initiation factors
main components of translation in prokaryotes
initiation factor
preinitiation complex
shine-dalgarno sequence
what is isoaccepting? how does it apply to the wobble hypothesis?
it is tRNA molecules with different anticodons for the same AA.
allowed by wobble hypothesis which is relaxation of pairing rules at the third base pair of the codon
what is the last component needed for initiation of translation
large subunit
2 types of prokaryotic gene regulation
negative and positive control
what makes a repressible operon system
gene end product represses gene expression
what makes an inducible operon system
induced by a certain environment
how does negative control in the lac operon work based on presence of lactose
present: lactose binds to repressor and changes conformation to prevent it from binding to operator region
absent: repressor binds to operator region preventing transcription
why is tryptophan operon considered repressible
repressor is normally inactive, presence of tryptophan activates repressor
binding of which complex increases ability of RNA polymerase to transcribe the lac-operon
Cap-cAMP
2 major mechanisms of epigenetic changes
Methylation: reversible
Histone modification/chromatin remodeling: alter accessibility of genes
N-term region of histone tails in AA can be modified by what 3 mechanisms
Acetylation(activate)
Phosphorylation(activate)
Methylation(repress or activate)
what is the second most common regulation
post transcriptional regulation
roles or DICER and RISC?
what system do they occur?
DICER: cleaves dsRNA into 21 fragments
RISC: combine miRNA and siRNA to remove one dsRNA
involved in mRNA silencing
mutations vs DNA polymorphisms
Mutations: uncommon, but lead to phenotype change
Polymorphism: more common, but usually neutral
4 mutation categories
spontaneous
induced
somatic
germ-line
point mutation
change of one base pair into another
missense mutation
point mutation resulting in AA change
nonsense mutation
point mutation resulting in a stop codon instead of an AA
silent mutation
point mutation that codes for the same AA
2 base pair mutations
transition: pyrimidine replaces pyrimidine and purine for purine
transversion: pyrimidine for purine or vice versa
3 reversion mutations
true reversion: one mutation creates missense, second mutation reverts it back to wild type
intragenic reversion: deletion mutation, corrected by a second addition mutation
second-site reversion: 3 genes make phenotype, mutation one changes function of one gene changing phenotype, mutation 2 changes function of another gen to cancel out first mutation
what type of mutation leads to size of Shetland ponies
missense
2 repair systems for DSBs
-NHEJ
-homologous recombination repair
what type of testing determines if a person is a carrier for a recessive disease
carrier genetic testing
is newborn genetic screening mandated in all 50 states
yes
what are the non invasive prenatal genetic techniques
Maternal serum screening
what is fetal cell sorting?
what diseases can it identify?
DNA and chromosome analysis
identifies cystic fibrosis and spinal muscular atrophy
cancer cells are _____, meaning they look and behave more like ______ cells.
dedifferentiated, primordial
what is metastasis
malignant tumor that moves to a new location and forms new tumors
T/F mutations in DNMT3A gene occur early in certain leukemias, normally its product helps methylate chromatin for gene silencing
TRUE
genes linked to increased susceptibility to breast and ovarian cancers
BRCA1 and BRCA2
T/F STRs are more than 10 bp while VNTRs are less than 10 bp
FALSE. VNTRs are typically longer and STRs are shorter
CODIS was written by the FBI and currently uses 13 _____ markers
short tandem repeat (STRs)
