DNA & Protein Synthesis: Replication, Mutations, and Genetic Code

What is the purpose of DNA replication?

To ensure that new cells have identical DNA strands.

Where does DNA replication begin?

At origins of replication.

What is the role of DNA helicase in replication?

It unwinds and separates the two DNA strands by breaking hydrogen bonds.

What are Okazaki fragments?

Segments of DNA synthesized on the lagging strand during replication.

What enzyme links Okazaki fragments together?

DNA ligase.

What does semi-conservative replication mean?

Each new DNA molecule consists of one old strand and one new strand.

What is the order of molecules in DNA replication?

DNA → RNA → Proteins → Traits.

What are the main differences between DNA and RNA?

DNA is double-stranded, contains deoxyribose, and has base T, while RNA is single-stranded, contains ribose, and has base U.

What is the function of messenger RNA (mRNA)?

To carry the DNA code out of the nucleus to the ribosomes.

What is transcription?

The process of making mRNA from a DNA template.

What is the role of RNA polymerase?

It synthesizes mRNA by binding to the promoter on DNA.

What are introns and exons in mRNA processing?

Introns are non-coding segments removed from mRNA, while exons are coding segments that are joined together.

What is a codon?

A set of three nucleotides on mRNA that codes for a specific amino acid.

What is an anticodon?

The three bases on tRNA that are complementary to a codon on mRNA.

What are point mutations?

Changes in a single nucleotide base in the DNA sequence.

What are frameshift mutations?

Mutations caused by insertions or deletions of bases that shift the reading frame.

What is a silent mutation?

A mutation that does not change the amino acid sequence of a protein.

What is sickle cell anemia?

An autosomal recessive disorder caused by a mutation in gene(s).

What is cystic fibrosis?

A genetic disorder caused by a mutation affecting ion transport across cell membranes.

What is the function of ribosomal RNA (rRNA)?

It makes up ribosomes and helps read mRNA to build proteins.

What happens during the editing of mRNA?

Introns are removed, and exons are spliced together before mRNA exits the nucleus.

What is the role of tRNA in protein synthesis?

It carries specific amino acids to the ribosome based on the mRNA codon.

How does DNA polymerase proofread DNA?

It checks and corrects errors during DNA replication.

What is the result of a nonsense mutation?

It creates a premature stop codon, leading to a shortened protein.

What is Chargaff's Base Pairing Rule?

The amount of Adenine must equal the amount of Thymine and the amount of Cytosine must equal the amount of Guanine.

What are purines?

Nucleotides with 2 rings.

Which base(s) are the purines?

Adenine and Guanine

What are pyrimidines?

Nucleotides with 1 ring.

Which base(s) are the pyrimidines?

Thymine, Uracil, and Cytosine

What is a promoter?

A specific region of DNA that acts as a binding site for RNA Polymerase to begin gene transcription.

Describe the (differences in) structure and function between mRNA, rRNA, and tRNA.

mRNA = single stranded, carries DNA out of nucleus, tRNA = folded single strand, binds amino acids to help build proteins, rRNA = makes up ribosomes and reads mRNA to help build proteins.

Where does transcription occur? Why?

In the nucleus, because, that is where DNA is stored, protecting it from other enzymes.

Where does translation occur? Why?

In the cytoplasm on ribosomes, because, that is where the necessary molecules, ribosomes, amino acids, and tRNA, are located.

What is the end result of protein synthesis? What types of bonds are used for these molecules?

Results in a polypeptide chain which folds into a protein. Covalent peptide bonds are used.

Describe the major different between point and frameshift mutations.

Point mutations affect one amino acid, frameshift mutations affect all the amino acids after it (chain reaction).

How many bonds do Adenine and Thymine have?

2 hydrogen bonds.

How many bonds do Cytosine and Guanine have?

3 hydrogen bonds.