Genetics Flashcards
what is the Central Dogma
DNA is transcribed to RNA, which is translated into amino acids to form a protein
what is epigenetics
a term used to describe changes that are made around the genome that do not alter the actual nucleotide
do histones give proteins a net positive or negative charge at the normal pH of the cell
positive
true or false - in animals, DNA is only found in the nucleus
false - it is also found in the mitochondria
what is the difference between euchromatin and heterochromatin
euchromatin is accessible to the cell’s translation machinery and only coiled during nuclear division
heterochromatin is not accessible to cellular machinery and will not be transcribed
what is the most common example of epigenetic regulation
DNA methylation
what is DNA methylation
involves the addition of an extra methyl to cytosine nucleotides and it causes DNA to be coiled more tightly
what is polyploidy
occurs when a cell has more than two copies of homologous chromosomes`
what happens during the initiation step of transcription
a group of DNA binding proteins (TFs) binds to the promoter on the DNA strand
what is the major enzyme of transcription
RNA polymerase
in what direction does RNA polymerase move along the DNA and what is the direction of the new RNA strand being made
3’->5’ and 5’->3’
how are activators and repressors regulated
they are allosterically regulated by cAMP
what is an operon
a genetic unit composed of a promoter, operator and genes
what are the 2 conditions needed to activate the lac operon
- lack of glucose
2. lactose is present
what is gene repression
when there is no lactose, the lac repressor protein binds to the operator site and prevents the transcription of lac genes
what are release factors
trigger termination of translation
true or false - proteins translated by free floating ribosomes function in the cytosol
true
what is the difference between a promoter and a primer
a promoter is a spot on the DNA that signals the RNA polymerase where to begin transcriptipn
a primer is a short piece of RNA that starts replication
what are the steps of mitosis
prophase, metaphase, anaphase, cytokinesis, telophase
what is involved in prophase of mitosis
sister chromatids are joined at centromeres; the centrioles move to opposite sides of the cell; the nuclear envelope disappears; the spindle forms and the kinetechore microtubules grow from the spindle and connect the centrioles
what is involved in metaphase of mitosis
chromosomes align along the middle of the cell on the microtubules
what is involved in anaphase of mitosis
the sister chromatids split from the centromeres and move to the opposite sides of the cell
what is involved in cytokinesis
the actual separation of the cellular cytoplasm
what is involved in telophase
decondensation of the chromosomes and the nuclear membranes reform
what is the result of mitosis
two identical daughter cells with each containing one complete copy of the parent’s genomes
what are point mutations
a mutation that changes a single nucleotide in a DNA
what is a transition mutation
a base substitution exchanging a purine to a purine or pyrimidine to pyrimidine
what is a transversion mutation
a base substitution exchanging a pyrimidine to a purine
what are the two types of point mutations
addition and deletion
what are the four mutations at the level of a chromosome
deletion, duplication, inversion and translocation
what is the difference between proto-oncogenes and oncogenes
proto-oncogenes stimulate normal growth in human cells whereas oncogenes cause cancer
what are the steps of meiosis
prophase 1, metaphase 1, anaphase 1, telophase 1
prophase 2, metaphase 2, anaphase 2, telophase 2
what is involved in meiosis 1
prophase 1 - homologous chromosomes line up beside each other to match their genes
metaphase 1 - the two homologous chromosomes remain attached and move to the metaphase plate
anaphase 1 - the pairs of homologous chromosomes separate to create haploid cells
telophase 1 - cytokinesis occurs and produces two daughter cells
what is the result of meiosis 2
the end result produces 4 daughter haploid cells
what is nondisjunction and when can it occur
this occurs in anaphase 1 or 2. it is when the centromere of a chromosome does not split therefore, one of the cells will have two extra chromatids and one of the cells will be missing one.
when does crossing over occur and what does it do
prophase 1 ; the exchange of DNA nucleotides
what is the number of chromosomes at the start and finish of replication
start = 46 chromosomes finish = 46 chromosomes, 92 chromatids (diploid with sisters)
what is the number of chromosomes at the start and finish of mitosis
start = diploid with sisters ; 46 chromosomes , 92 chromatids finish = 46 chromosomes
what is the number of chromosomes at the start and finish of meiosis 1
start = diploid with sisters ; 46 chromosomes , 92 chromatids finish = haploid with sisters ; 46 chromosomes , 92 chromatids
what is the number of chromosomes at the start and finish of meiosis 2
start = haploid with sisters ; 46 chromosomes, 92 chromatids finish = haploid ; 23 chromosomes
what is the mendelian ratio
3:1
what is the law of segregation
alleles segregate independently when forming gametes during meiosis
what is the law of independent assortment
genes located on separate chromosomes assort independently; i.e when genes code for different traits, on separate chromosomes, they do not affect each other
what is the equation that predicts the genotype frequencies of a gene with only two alleles in the Hardy Weinberg population
p^2 + q^2 + 2pq = 1
