Final exam material Flashcards
Homozygous
both alleles are the same (either recessive or dominant)
Heterozygous
Both alleles are different (dominant and recessive)
Incomplete dominance
Neither allele is fully dominant, both MIX together
White + black = gray
Codominance
Both alleles are expressed and can be noticed
White + black = black and white speckled fur
Polygenic inheritance
inheritance based upon multiple genes
Sex linked inheritance
Certain genes are only found on the X or Y chromosome
*note that girls get an X from both their father and mother
Boys get a Y from dad and X from mom
Linked genes
Genes that aren’t likely to separate during crossing over as they are close together on the chromosome
Epistasis or gene masking
Expression of one gene mask the expression of another
Ex. gene that makes people bald mask the expression of hair color
Semiconservative DNA replication
each daughter cell receives one old strand and one new strand
*this one is the one that actually happens
Purines
Larger double ring structure
Adenine and guanine
Pyrimidines
Smaller single ring structure
Thymine and cytosine
DNA structure
Sugar phosphate backbone held together by phosphate diester bonds
Nitrogenous bases (ATGC) bond together in the middle with hydrogen bonds
Replication bubble
site on DNA where DNA splits so it may be replicated
Helicase
enzyme that splits the hydrogen bonds of nitrogenous bases in order to separate DNA
Primase
enzymes that synthesis primers (short RNA sequences that create a starting point for DNA synthesis)
*DNA polymerase III can only add to existing three strands, that’s why this is necessary
How are Okazaki fragments made
The lagging strand of DNA synthesizes away from the replication fork, this means that the template DNA will be unwound behind the current primer necessitating the need for a new one, creating another Okazaki fragment
Energy transmission in adding nucleotides
cleaves the phosphodiester bond on the three end of the existing nucleotide and uses that to add it to the newly attached nucleotides
Topoisomerase
responsible for relieving the tension on the DNA strand at the replication bubble by cutting the DNA strands
Point mutations
affect one or small number of base pairs
Silent mutation
The RNA sequence still codes for the same string of amino acids as the non mutated version
non-sense mutation
addition of a point mutation leads to a premature stop coding usually making the protein unfunctional
frame-shift
addition or subtraction of nucleotides into the DNA sequence, leading to the current nucleotides to shift over a particular number
break down transcription
1.RNA polymerase binds to promoter sequence (specific DNA sequence that signals where polymerase should bind)
- adds corresponding RNA nucleotides
- reaches stop sequence
Differences in transcription between prokaryotes and eukaryotes
in prokaryotes, the sigma protein recognizes the promoter and helps RNA polymerase bind, in eukaryotes they use transcription factors
3 versions of RNA polymerase vs 1 in prokaryotes
*note that during transcription, prokaryotes can start translating the mRNA while eukaryotes do not posses this ability
introns and exons
exons are the sequences that are translated into proteins
Introns are the sequences in the middle that aren’t included during RNA splicing
*this allows for alternative splicing(different proteins made from the same DNA sequence) as certain exons can be left out
describe initiation of RNA translation (protein synthesis)
small sub unit connects to mRNA strand
start codon on this strand binds to one end of tRNA
larger subunit the binds to other end of tRNA
Repressor proteins
type of protein that binds to DNA to halt transcription
Activator proteins
type of protein that binds to DNA to start transcription
Operons
two genes located close together on bacterial DNA, they both code for different proteins but the proteins are functionally related
Operators
DNA sequences in front of a protein coding gene sequence
repressor proteins can then bind to the operator sequence, halting translation of a certain gene
Methyl groups effect on DNA
triggers chromatin condensation making DNA less accessible
Acetyl groups effect on DNA
triggers chromatin decondensation making DNA more accessible
Apoptosis
programmed cell death
*ex. neurons that don’t establish connections early on will die
Ligase
In the context of DNA, ligase connects nucleotides with phosphodiester bonds
*important during DNA replication
why are the poly(A) tail and 5’ cap needed on mRNA
prevents the mRNA from being degraded by enzymes
-35 and -10 boxes
found in prokaryotic cells, necessary for specificizing where the sigma protein needs to bind
telomerase
Adds DNA to end of telomeres lengthening the chromosomes, this extends the lifespan of the cell and how many times it can divide
Codon
triplet of nucleotides that code for specific amino acid
