DNA Replication
What is DNA replication?
Making two identical copies of DNA from one original molecule.
What is the monomer that makes up proteins?
Amino acid
What type of protein speeds up chemical reactions in cells without being consumed?
An enzyme.
What is a mutation?
A sudden, permanent change in the DNA nucleotide base sequence of an organism.
What does ligase do?
It joins pieces of DNA together.
Which strand is built in Okazaki fragments?
Lagging strand.
Which type of protein has a mechanical role. For example, keratin or collagen?
Fibrous proteins
What is an active site?
The region on an enzyme where the substrate binds.
What are two or three common mutagens?
Radiation, cigarette smoke, alcohol, viruses.
What is the purpose of gene cloning?
To make many copies of a gene to study or manipulate it.
Describe the difference between the leading and lagging strands.
Leading strand is built continuously toward the fork; lagging strand is built in fragments away from the fork.
Name the two main steps of protein synthesis and where each occurs in a eukaryotic cell.
Transcription: in the nucleus
Translation: in the ribosome
What is the difference between anabolic and catabolic enzymes?
Anabolic enzymes: build larger molecules from smaller ones.
Catabolic enzymes: break down large molecules into smaller ones.
Distinguish between somatic and germline mutations?
Somatic mutations: occur in body cells and cannot be inherited.
Germline mutations: occur in the gametes and can be inherited.
What role do restriction enzymes play in gene cloning?
They cut DNA at specific sequences, which isolates the desired gene.
What is Semi-conservative DNA replication?
The process where a double-stranded DNA molecule separates into two strands, each acting as a template for a new complementary strand.
During translation, what is the role of tRNA?
tRNA brings the correct amino acid to the ribosome by matching its anticodon to the mRNA codon.
What happens to an enzyme when the temperature rises above its optimum. For example, above 40°C in humans?
The enzyme denatures, its shape changes, and it stops functioning.
Why are mutations in gametes more significant for future generations than mutations in skin cells?
Because gamete mutations can be inherited, while somatic (body cell) mutations can't.
Explain the difference between sticky ends and blunt ends in DNA fragments.
Sticky ends: have overhanging single-stranded DNA that can easily attach to complementary sequences.
Blunt ends: are cut straight across with no overhangs.
Explain how Okazaki fragments are joined together.
DNA polymerase I replaces the RNA primers with DNA, then ligase connects the sugar-phosphate backbone to form a continuous strand.
What is redundancy/degeneracy?
The property of the genetic code where multiple codons can code for the same amino acid.
Why does pepsin work best in the stomach while trypsin works best in the small intestine?
Because each enzyme has an optimal pH that matches the environment where it functions.
How can non-disjunction during meiosis lead to genetic disorders in offspring?
It produces gametes with extra or missing chromosomes, which lead to conditions like trisomy or monosomy after fertilization.
Describe how a vector is used in gene cloning.
A vector (such as a plasmid or virus) carries foreign DNA into a host organism where it can be replicated or expressed.