test 6- genetics part 2 Flashcards
(54 cards)
protien synthesis
the process of reading instructions in DNA to make a polypeptide
polypeptide
a chain of amino acids, can bind to others and fold into a protein
transcription
DNA is copied into a completmentary strand of mRNA
genetic code
code of instructions for how to make proteins
codon
a set of 3 nucleotides on the mRNA
anticodon
“complementary” 3 nucleotides on tRNA
amino acid
monomer (building block) for making proteins, held together by peptide bonds
translation
interpreting the RNA message into a polupetide to make a protien
epigenetics
the study of changes in gene expression that are heritable
what is the central dogma of genetics?
DNA—>transcription, RNA—>translation, protein
why does making proteins have to be a two step process?
because DNA is located in the nucleus and can’t leave, but protiens are made in ribosomes so there has to be a way to get it out by changing it to something that can leave the nucelus
what is mRNA’s role in protein synthesis?
-copies instruction in DNA
-carries them out to the ribosomes in the cytoplasm
what is tRNA’s role in protein synthesis?
-binds and carries specific amino acids tot the ribosome
what is rRNA’s role in protein synthesis?
-along with proteins, make up the ribosome
-help catalyze formatino of specific bonds
where does transcription take place?
in the nucleus
what are the steps of transcription?
-unzip the gene that needs to be copied
-use complementary base paring rules to match RNA nucleotides with the exposed DNA nucleotides
-release the completed mRNA molecule
-DNA zips back up and the mRNA leaves the nucleus and enters the cytoplasm
where does translation take place?
in the ribosomes which are in the cytoplasm
what are the steps of translation?
-mRNA attaches to a ribosome
-ribosome reads the mRNA molecule codons starting at AUG
-tRNAs act like taxis to pick up and drop off the amino acides that match with each codon
-tRNAs continue to drop off amino acids and the ribosome binds the amino acids together by peptide bonds
-when the “stop” codon is reached, the ribosome releases the completed polypeptide chain
what are the base pairing rules for DNA to mRNA?
A—>U
T—>A
C—>G
G—>C
how is gene expression regulated?
-regulatory proteins called transcription factors control gene activity and basically turn genes on and off
-repressors decrease transcription (off)
-activations increase transcription (on)
-happens a lot in cell differentiation
what is the difference between epigenetics and mutation?
-epigenetics are changes in gene EXPRESSION that are heritable
-mutations are a change in DNA SEQUENCE
-epeigenetics don’t affect the actual DNA, just how it is expressed
what is a possible consequence of an error made in transcription or translation?
-if an error is made in transcription then it will get the codon wrong and code for the wrong amino acid and then it will make a completley different protein
-not only will you have a defecit of the protein that you need, you will have an excess of one you don’t
-then you can’t do whatever function you needed to
what kind of bonds hold nitrogen bases together?
hydrogen
what types of RNA are involved in transcription?
mRNA
