Genetics Flashcards
genotype determines
phenotype
genome
entire collection of genetic material in a cell or virus
gene
heritable units of genetic material that defines a particular trait
genotype
genetic makeup
phenotype
physiological or physical traits
DNA
deoxyribonucleic acid
RNA
ribonucleic acid
chromosomes
genome organized into packaged strands of DNA
number does not influence organism complexity
prokaryote chromosomes
1 - 3 chromosomes
typically circular
eukaryotic chromosomes
numerous linear chromosomes
histones
mitochondria and chloroplasts have chromosomes similar to prokaryotes
histones
DNA wrapped around
compressed into chromatin fibers
plasmids
circular and extrachromosomal
nucleic acids are built from
nucleotides
parts of a nucleotide
phosphate
sugar
nitrogen base
RNA
what does phosphate do
link nucleotides
what are the two types of sugars
deoxyribose and ribose
what are the two types of nitrogen bases
purine and pyrimidine
DNA is a
double helix
RNA is a
single strand
DNA strands are
antiparallel
central dogma of biology
DNA transcribes RNA
RNA translates into protein
DNA replication is
the process by which a cell copies its genome before division
typically fast and accurate
few mutations, but there is proofreading
semiconservative
semiconservative process
1 parent strand and 1 new strands
leading strand
continuous replication
lagging strand
discontinuous replication
DNA Polymerase III
places DNA
DNA Polymerase I
replaces RNA primer with DNA
ligase
glues the strand together
okazaki fragments
disjointed DNA fragments that need to be linked together
eukaryotic DNA replication
takes longer and needs more factors
multiple replication sites
slower
gene expression
make proteins
transcription steps
initiation
elongation
termination
initiation
start
elongation
build
termination
stop
where does transcription take place in prokaryotes
cytoplasm
where does transcription take place in eukaryotes
nucleus
RNA polymerase
binds to promoter
places complementary ribonucleotides
continues until termination site
eukaryotic cells have
exons
introns
spliceosomes
alternative splicing
exons
necessary information
introns
extra bits, unneeded
spliceosome
remove introns and join exons
alternative splicing
create alternative products from same base materials
very tightly regulated
where does the mRNA go after the nucleus in eukaryotic cells
the ER
prokaryotic cell RNA splicing
no introns
no mRNA
types of RNA
mRNA
tRNA
rRNA
mRNA
messenger RNA
carries genetic code
tRNA
transfer RNA
brings amino acids to build protein
rRNA
ribosomal RNA
builds ribosomes
codons are made up of
3 nucleotides
how many triplet codes are there
64
how many coding codons are there
60
how many stop codons are there
3
how many start codons are there
1
protein synthesis comes from
mRNA template
where does translation take place in all cells
cytoplasm (ER in eukaryotes)
ribosomes
rRNA and proteins
EPA sites
large and small subunits
A site
aminoacyl-tRNA binding site
new guy comes in
P site
peptide-tRNA binding site
new guy binds
E site
exit site
tRNA exits
in eukaryotic cells most mRNA encodes for
single protein
in prokaryotic cells mRNA is commonly
polycistronic
polycistronic
one strand encodes multiple genes and makes proteins right off the bat
post-translational modification
can occur, mostly in eukaryotes
how much of a cells genome is expressed at any given time
20%
constitutive genes
housekeeping genes
constantly made
facultative genes
have an on/off
pre-transcription regulation
operons
operons
collection of genes controlled by shared regulatory elements
parts of an operon
promoter
genes
repressor
operator
promoter
region RNA polymerase binds to
repressor
protein that turns gene off
operator
DNA sequence the repressor binds to
inducible operon
OFF by default
repressible operon
ON by default
example of an inducible operon
lactose operon
example of a repressible operon
arginine operon
mutations
change in the genetic material of a cell or virus
can be good, neutral, or bad
types of mutations
substitution
insertion
deletion
substitution
incorrect nucleotide added in place of what is supposed to be there
insertion
addition of one of more nucleotides
deletion
removal of one or more nucleotides
neutral (silent) mutation
amino acid does not change
missense mutation
wrong amino acid in protein
nonsense mutation
early stop, do not have full protein
reversion mutation
change back to normal
frameshift mutation
alters all amino acids at and after insertion/deletion
spontaneous mutations
naturally occurring due to error in DNA replication
important for evolution
mutagens
agents that increase rate of mutation
carcinogens
mutagens that promote the development of cancers
chemical mutagens
organic or inorganic agents
arsenic, asbestos, tobacco smoke
physical mutagens
UV light, x-rays, radioactive gamma rays
biological mutagens
cause recombination
certain viruses, transposons
recombination
exchange of genetic material that leads to new combinations
what has proofreading capabilities
DNA polymerase
excision repair
damaged DNA is clipped and removed
DNA Pol I lays down new nucleotides
in single-celled organisms, more damage than repair leads to
death
in animals, more damage than repair leads to
cancer
vertical gene transfer
cells passing genetic information from parent cell to offspring
horizontal gene transfer
passing genetic information between cells independent of cell division
types of horizontal gene transfer
conjugation
transformation
transduction
transposons
conjugation
not sexual reproduction
requires fertility plasmid
needs pilus
pilus
allows for conjugation to occur
the bridge between cells
transformation
take up DNA from environment
Griffith’s Experiment
1920s
Frederick Griffith
discovered transformation
transduction
introduction of new genetic material into bacterial cell by a bacteriophage