DNA structure, replication, transcription, translation, and mutations test

DNA's function in an organism:

stores and carries genetic information

Structure of DNA:

double helix (double stranded)

What base pairs are in DNA?

A-T

G-C

Components of a nucleotide:

nitrogenous base, phosphate, sugar

What are the bonds between nitrogen bases called

hydrogen bonds

What is RNA's structure?

single stranded

What base pairs does RNA have?

A, U, G, C

What is the relationship between genes and proteins?

A gene is a segment of DNA that carries a code, written in a sequence of nucleotides, which tells the cell how to build a specific protein.

What is transcription?

The process of turning DNA into RNA

Where does transcription take place?

inside the nucleus

What are the three steps of transcription?

initiation, elongation, termination

What happens during initiation in transcription?

RNA polymerase recognizes and binds to a promoter region on double stranded DNA and unwinds the strand

What happens during elongation in transcription?

-RNA polymerase II adds complementary base pairs to DNA template strand

-As elongation occurs, completed portions of mRNA are released

What happens during termination in transcription?

A stop codon is reached which marks the ending of transcription

What is the template strand?

The original strand that is being used to copy and make complementary pairs.

Which strand is the non coding strand?

template strand-(3' to 5')

Which strand is the coding strand?

non-template strand- (5' to 3')

Which strand do you use to identify the amino acid when using the codon chart?

mRNA strand

What is a codon?

a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

What is an exon?

An exon is a coding region; it gets spliced

What is an intron?

An intron is a non coding region; it gets removed

What is the purpose of the poly-A tail?

The presence of the poly(A) tail increases the stability of the mRNA molecule through the interaction of proteins

What is the purpose of the 5' cap?

Protects from degradation; involved in translation initiation

Why is the splicesome significant?

it removes introns and splices exons; it turns a immature RNA into a mature mRNA

What is mRNA and its function

mRNA (messenger RNA) is the form that carries the instructions for making proteins and is made during transcription.

What is tRNA and its function

tRNA (transfer RNA) is the form that carries amino acids

What is rRNA and its function

rRNA (ribosomial RNA) is the form that makes up part of the structure of the ribosomes

What is translation?

the decoding of an mRNA message into a protein

Where does translation take place?

cytoplasm

What are the 3 steps of translation?

initiation, elongation, termination

Initiation of translation:

The ribosome attaches to the mRNA at the start codon (AUG).

Elongation of translation:

Amino acids are brought and the ribosome helps link these amino acids together, forming a growing protein chain.

Termination of translation:

When the ribosome reaches a stop codon (UAA, UAG, or UGA), translation ends. No tRNA matches these codons, so a release factor helps separate the protein from the ribosome, and the process is complete.

Protein synthesis diagram:

If the DNA codon was AGC what would the mRNA codon be?

UCG

If the DNA code was AAA what would the mRNA be?

UUU

What would amino acid of GUC be?

What is a mutation?

change in DNA sequence

What is a point mutation?

a change in a single nucleotide

What is substitution?

When one base is substituted for another

What are the kinds of point mutations?

silent, missense, nonsense

What is a nonsense mutation?

an early stop codon is present- shortening the protein

What is a missense mutation?

one amino acid substituted for another

What is a silent mutation?

no change in protein- the amino acid isn't affected

What is a frameshift mutation?

The "reading frame" is shifted, changing the entire protein.

What are the kinds of frameshift mutation?

insertion and deletion

What happens during insertion?

an extra base is inserted into a codon

What happens during deletion?

a base is removed

Are mutations positive or negative?

They can be both

What is an example of a positive mutation?

lactose tolerance

What is an example of a negative mutation?

sickle cell anemia