Honors Bio - Unit 7: DNA, Protein Synthesis, Gene Expression, & Mutations

transcription

replicating a gene into mRNA

promoter region

the beginning of a gene that will be transcribed

introns

meaningless segments that are removed from pre-mRNA

exons

expressed segments, remains in final mRNA transcript

mRNA

a copy of a gene that is used to make proteins

5’ cap and 3’ poly-A tail

protects both ends of the mRNA transcript

tRNA

transfers specific amino acids to the correct position along the mRNA, has an anticodon that helps to find the correct position

translation

the process of making proteins from the mRNA code

codon

a group of 3 consecutive bases which codes for a specific amino acid

anticodon

a specific region of tRNA that is complementary to a specific mRNA codon

genome

complete genetic code found in an individual

gene

a region of DNA that is transcribed and translated to make proteins

lactose intolerance

body doesn’t make enough of the enzyme lactase which is needed to digest lactose, when it passes through the large intestine, bacteria ferments it into energy for itself causing cramps, stomach pain, & diarrhea

structural genes

codes for the enzymes needed to break down lactose

promoter region

the beginning of a gene where RNA polymerase binds to begin transcription

operator

segment where repressor proteins bind that is in between the promoter region and the gene, blocks transcription and eventually prevents protein synthesis

operon

series of genes that codes for specific proteins and the proteins that prevent the expression of that gene

ONLY IN PROKARYOTES

LAC Operon

operon required to produce the enzymes needed to digest lactose

regulator gene

codes for repressor proteins that prevent the transcription of a specific gene

repressor protein

protein that prevents a specific gene from being transcribed, binds to the operator in between the promoter region and the gene and prevents RNA polymerase from binding to that gene

inducer

a chemical that initiates gene expression by binding to the repressor protein and removing it from the operator

gene activation

process of initiating transcription by removing repressor proteins from the operator

alternative splicing

a process by which different combinations of exons are joined or skipped in a pre-mRNA transcript, leading to many possible proteins (isoforms) to be encoded by a single gene

ONLY IN EUKARYOTES

point mutation

a change to a single nucleotide in DNA or mRNA that affects the amino acid sequence, leading to an incorrectly made protein

addition frameshift

adding a base to the DNA or mRNA sequence

deletion frameshift

removing a base from the DNA or mRNA sequence

substitution

replacing one base with another in a DNA or mRNA sequence; does not cause a frameshift

missense mutation

amino acid is changed to a different amino acid

depends - may result in diabetes, may not change protein, or improves protein function (RARE)

nonsense mutation

amino acid is changed to a “stop”

bad - no protein

silent mutation

one nucleotide changes, but it still codes for the same amino acid since one amino acid has a few possible codon combinations

good

AUG

start codon, codes for methionine

chromosome

the structure that carries the DNA and all the genetic information in a cell

histone

a protein that provides structural support for a chromosome, chromosome wraps itself around this structure to give itself a more compact shape

rRNA

makes up the structure of a ribosome

snRNA

small nuclear RNA; forms the spliceosome that helps to modify mRNA before it leaves the nucleus

polypeptide

chain of amino acids that folds into a 3D shape to make a protein

Central Dogma

theory stating that genetic information in a cell flows DNA → RNA → Protein

RNA polymerase

an enzyme that transcribes DNA into a mRNA transcript during transcription

electrophoresis

a technique using an agarose gel and electric current to distinguish between individual’s DNA or differences between normal and abnormal proteins based on size and charge

restriction enzymes

cuts DNA at specific base sequences to make smaller fragments that are easier to analyze

fragments move from a (-) pole to a (+) pole

RFLP

a unique banding pattern on an individual’s DNA after being treated by several restriction enzymes

genetic fingerprint