protein synthesis and mutation

bio 1 test review

What is the central dogma of biology?

one gene = one enzyme

the flow of genetic info in our bodies

dna → rna → protein

the building block or monomer of dna

nucleotide

how many total chromosomes do we have

46

What are the three differences between RNA and DNA

RNA is single-stranded, contains ribose sugar, and has uracil instead of thymine, while DNA is double-stranded, contains deoxyribose sugar, and has thymine.

What nucleotide does DNA have that RNA does not

Thymine, which is not found in RNA.

What nucleotide does RNA have

uracil

What are proteins made of? How many building blocks are there

Amino acids.  There are 20 different amino acids

What are the three types of RNA

mRNA, rRNA, tRNA

Describe the job or function of each of the three types of RNA, what does each of the letters mean that are before the RNA

mRNA- messenger RNA.  Copies the DNA during transcription.

tRNA - transfer RNA.  Brings amino acids to the ribosome during translation

rRNA - ribosomal RNA  What ribosomes are made of.

What are the two steps of protein synthesis? Which happens first?

Transcription then translation

Where does step one of protein synthesis occur

in the nucleus

In step one, DNA is transcribed into

mRNA

What are the three stages of Transcription and what happens in each

1. Initiation:  RNA polymerase attaches to the unzipped DNA. 

2. Elongation:  RNA polymerase builds the mRNA strand by complementary base pairing with the DNA.

3. Termination: the new mRNA falls off the strand.

What enzyme facilitates DNA transcription

RNA polymerase

What are the three things that happen during transcript modification

5’ Cap is added, Poly-A tail is added, and Introns are removed.

What are INTRONS and EXONS? Which stays in the nucleus and which one leaves

Introns are non-coding regions of mRNA that are cut out by spliceosomes and stay in the nucleus.

Exons are coding regions that remain in the mature mRNA strand, and leave the nucleus to be made into a protein.

What complex acts like a pair of scissors and cuts out the noncoding portion of the preRNA

Spliceosome

What travels out of the nucleus after DNA transcription

Mature mRNA (an mRNA that only has Exons, a 5’ cap, and a poly A tail)

Where does step two occur

ribosome

In step two, mRNA is translated into

polypeptide (protein)

What are the three stages of Translation

Initiation, Elongation, Termination

What organelle makes proteins

ribosomes

What is a polypeptide

A protein made of an amino acid chain

What are codons? What are anticodons? Where can you find each

Codons are 3 nucleotide sequences read on the mature mRNA strand.

Anticodons are complementary to mRNA codons, found on the bottom of tRNAs

What is the start Codon and what amino acid does it code for

AUG, Methionine

How many stop Codons are there

3

How many subunits is a ribosome composed of

2 subunits,  one large, one small

What is the job of tRNA

Bring amino acids to the ribosome

Define Mutation

change in a cell’s genetic information

Define Mutagen

a substance or source that can damage or change DNA

What are the three potential results of a point mutation

Silent - the same amino acid chain results and no protein change

Nonsense- a premature STOP codon stops amino acid production

Missense - a new amino acid chain results.  Could be low impact if it’s conservative, or high impact if it’s non-conservative.

What two mutations result in a frameshift

Insertion or Deletion

What is a “frameshift”

A shift in how the codons are read, either by adding or subtracting a nucleotide.  The result is a completely different amino acid chain and protein.