Gene Expression

What is the central dogma of genetics?

DNA, RNA, Protein

The process by which information in a gene is used to produce a functional product, usually a protein

Gene expression

What did Garrod’s research on alkaptonuria help establish?

The relationship between genes, proteins, and phenotype

A defective/missing enzyme cannot properly degrade homogentisic acid, causing it to accumulate

Alkaptonuria

What type of inheritance does alkaptonuria follow?

Recessive inheritance

What organism did Beadle and Tatum use in their experiments?

Neurospora (bread mold)

What did Beadle and Tatum’s experiments show?

Specific DNA mutations can cause a loss of enzyme activity

What hypothesis did Beadle and Tatum propose?

One gene, one enzyme hypothesis

What are proteins made from?

Amino acids

How many different amino acids are used in protein synthesis?

20

What bonds connect amino acids in proteins?

Covalent peptide bond

What is a codon?

Sequence of three mRNA nucleotides

What does each codon specify?

One amino acid/stop signal

How many possible codons are there?

64

Why are there 64 codons?

4 nucleotides and 3 positions (4³)

Multiple codons can code for the same amino acid

Redundancy

What is the start codon?

AUG

What amino acid does AUG code for?

Methionine

What are the three stop codons?

UAA, UAG, UGA

Signals that translation should end

Stop codon

In the nucleus, genetic information encoded in a gene is copied into a pre-mRNA molecule

Transcription

Pre-mRNA is processed into mRNA, which leaves the nucleus through a nuclear pore and moves into the cytoplasm

mRNA processing

Genetic information in the mRNA is converted into an amino acid

Translation

RNA polymerase binds to the promoter sequence of the template strand of DNA

Initiation

Further unwinding of the DNA helix

Elongation

RNA polymerase reads the template strand and synthesizes the pre-mRNA molecule

Elongation

Release of RNA polymerase and pre-mRNA from template DNA

Termination

What sections of mRNA are snipped out?

Intron

Allows for one gene to code for more than one protein

Alternative splicing

What does each transfer RNA contain?

Anticodon

Contains an anticodon region that recognizes and binds to its complementary codon in mRNA

Transfer RNA

What are the steps of translation?

Initiation, elongation, termination

mRNA first binds to small ribosomal subunits, initiator tRNA, and large ribosomal subunit

Initiation

Amino acids are added to the growing polypeptide chain

Elongation

Ribosomes reach the stop codon

Termination

A functional, fully assembled macromolecule in a cell

Protein

Another term for a single amino acid chain

Polypeptide

Molecular “bridges” that connect mRNA codons to the amino acids they encode

Transfer RNA

Part of the ribosome that decodes the genetic message

Small subunit

Part of the ribosome that catalyzes peptide bond formation

Large subunit

The collection of proteins in a given cell type

Proteome

The amino acid sequence in a polypeptide chain

Primary structure

The pleated or helical structure in a protein molecule determined by bonds between amino acids

Secondary structure

The folding of secondary structures

Tertiary structure

The physical association of two or more polypeptide chains in one protein

Quaternary structure

Can cause protein mis folding

Genetic mutations

What percentage of genes are expressed in any given cell?

5-10%

What does the addition of methyl groups do to cytosine bases in DNA?

Turns promoter off

What does lengthening the poly A tail do?

Increases translation of the mRNA molecule

What does shortening of the poly A tail do?

Decrease translation of the mRNA molecule