Bio Test Protein Synthesis

Relationship between DNA, a chromosome, and genes

Both chromatin and chromosomes are made of a long DNA molecule wrapped around proteins. (Histone) Genes are segments of DNA that code for proteins.

What are the building blocks of DNA or all nucleic acids?

Nucleotides

3 components of a nucleotide

Phosphate group, pentose sugar, and nitrogen base.

Difference between Purines and Pyrimidines?

Purines have 2 rings while pyrimidines have 1. Purines contain Adenine and Guanine while Pyrimidines contain Cytosine, Thymine (which is in DNA) and Uracil (which is in RNA).

What sugar is apart of a DNA nucleotide?

Deoxyribose

What sugar is apart of a RNA nucleotide?

Ribose

What type of bond holds together a single strand?

Covalent bonds

What type of bonds holds together the 2 DNA strands?

Weak hydrogen bonds

How are the 2 strands in a DNA molecule oriented to each other?

They are parallel but they run in opposite directions so they are anti-parallel.

What is the name of the model for DNA replication? Why?

Semiconservative model because one strand is old/original and one strand is new.

Process of DNA replication

2 strands are untwisted and separated by the helices. Each original strand serves as a template for a new complementary strand. DNA polymerase adds new complementary nucleotides to the exposed bases of the original strand making a new strand. Each resulting DNA molecule is identical to the parent DNA molecule.

DNA vs RNA length

DNA: Large 100s-1000s of genes, RNA: Small 1 gene

DNA vs RNA strandedness

DNA: Double stranded, RNA: Single stranded

DNA vs RNA sugars

DNA: Deoxyribose, RNA: Ribose

DNA vs RNA bases

DNA: Adenine, Thymine, Guanine, Cytosine, RNA: Adenine, Uracil, Guanine, Cytosine.

What is happening during transcription?

A gene from DNA is copied to a small mRNA.

Why does transcription take place?

Genetic material is protected - mRNA delivers instructions to the organelle where proteins are made, increases speed of protein production - making many copies of mRNA.

Process of transcription.

RNA polymerase is the enzyme necessary for transcription. It binds to the promoter region and unwinds and separates DNA strands at the start point of the gene breaking weak hydrogen bonds. The enzyme recognizes that region because of the TATA box. Starts matching RNA nucleotides to DNA template. Once it’s passed the terminator region where the RNA, DNA, and enzyme are all released the process is complete.

Where does the RNA molecule go after transcription is complete? How does it get there?

Goes to the cytoplasm through nuclear pores to the ribosome.

What is happening during translation?

mRNA binds with the ribosome which reads mRNA and uses the info to make a protein.

Where does translation take place?

On the ribosomes in the cytoplasm

Function of mRNA during translation?

Carry genetic information from a cell's DNA to the cytoplasm

Function of tRNA during translation?

Bring amino acids to ribosomes to build protein

Function of rRNA during translation?

Helping to form ribosomes that read and translate mRNA into amino acids

What are the building blocks of proteins? How many are there and where do we get them from?

Amino acids. There are 20 and we obtain them from our diet or made by cell.

What enzyme attaches a specific amino acid to a specific tRNA molecule?

Aminoacyl-tRNA synthetase.

What is a codon?

A sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis.

What is an anticodon?

An anticodon is a sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on mRNA.

What are the sequence of events that happen during initiation of translation?

Small ribosomal subunit binds to 5’ end of mRNA. Initiator tRNA binds to start codon (AUG). The large ribosomal subunit binds so tRNA is in the P site.

Describe how amino acids are added to the growing protein at the ribosome.

What happens to terminate translation?

Stop codon reached at A site of ribosome. Release factor binds to stop codon at A site. Release factor breaks bond between tRNA and protein. All components dissociate.

What makes one protein different from another?

What is a mutation?

A change in genetic material of a cell.

What factors can cause mutations?

Mistake when replicating DNA, UV rays, X-rays, nuclear radiation, chemicals in cigarettes/vape smoke.

What is a point mutation?

Changes in one base pair of a gene.

What are 2 examples of point mutations?

Base pair substitution - one nucleotide is replaced by another, Base pair insertions or deletions - additions or losses of nucleotides within a gene.

Explain how silent mutation affects the resulting protein

New codon still encodes for the same amino acid.

Explain how missense mutation affects the resulting protein

New codon encodes for a different amino acid.

Explain how nonsense mutation affects the resulting protein

New codon is a stop codon and the protein is usually dysfunctional.

Explain how frameshift mutation affects the resulting protein

The reading frame for the codons will be altered down stream from the mutation. Usually results in dysfunctional genes.

What does DNA polymerase do during DNA replication?

DNA polymerase adds new complementary nucleotides to the exposed bases for the original strand making a new strand.

How is the order of amino acids determined?

The sequence of codons in mRNA determines the order of amino acids. That mRNA sequence came from a gene’s DNA sequence.