AP BIO Unit 6 Gene Expression and Regulation

What does Chargaff's rule state regarding nucleotides in DNA?

The amount of adenosine equals the amount of thymine and the amount of cytosine equals the amount of guanine.

What are the two types of nitrogenous bases in DNA?

Purines (A, G) with a double ring structure, and pyrimidines (C, T, U) with a single ring structure.

How are base pairs held together in DNA?

Base pairs are held together by hydrogen bonds.

How many hydrogen bonds are formed between adenine and thymine?

2 hydrogen bonds.

How many hydrogen bonds are formed between cytosine and guanine?

3 hydrogen bonds.

What is the structure of DNA?

DNA is a double stranded helix.

What is the backbone of DNA made up of?

The backbone of DNA is made of sugar and phosphate.

What does it mean for DNA strands to be antiparallel?

One strand runs 5’ to 3’ while the other runs 3’ to 5’.

What is at the 5’ end of a DNA strand?

A free phosphate group.

What is at the 3’ end of a DNA strand?

A free hydroxyl group.

What is the primary source of heritable information in organisms?

DNA.

In some viruses, what serves as the primary source of heritable information?

RNA.

Where is DNA found in eukaryotic cells?

In the nucleus.

How is DNA structured in prokaryotic cells?

Prokaryotic DNA is circular and located in the nucleoid region.

What are plasmids?

Small, circular DNA molecules found in prokaryotes that replicate independently from chromosomal DNA.

How can plasmids be useful to prokaryotes?

They contain genes that may be useful in certain environments but are not essential for survival.

What is the process of DNA replication?

The process by which DNA makes a copy of itself.

During which phase of the cell cycle does DNA replication occur?

During the S phase.

What is the semi-conservative model of DNA replication?

Each parental strand makes a copy, resulting in two daughter molecules each with one parental and one new strand.

What are Okazaki fragments?

Segments of the lagging strand synthesized during DNA replication.

What is the role of DNA ligase in DNA replication?

It joins Okazaki fragments to form a continuous DNA strand.

What are the three types of RNA?

Messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).

What occurs during transcription?

Synthesis of RNA using information from DNA.

What is the codon?

A sequence of three nucleotides on mRNA that corresponds to an amino acid.

What is the universal genetic code?

61 codons code for amino acids, while 3 are stop codons.

What is alternative splicing?

A process by which a single gene can code for multiple polypeptides by splicing pre-mRNA differently.

What is the function of transfer RNA (tRNA)?

tRNA carries specific amino acids to the ribosome and matches them with the corresponding codon on mRNA.

What are the functions of the A, P, and E sites in the ribosome during translation?

A site holds the tRNA carrying the next amino acid, P site holds the tRNA with the growing polypeptide, and E site is where tRNA exits.

What is the role of chaperone proteins?

They assist in the correct folding of polypeptides.

What is a retrovirus?

A type of virus that reverses the usual flow of genetic information from RNA to DNA using reverse transcriptase.

What is an operon?

A group of genes that can be turned on or off together in prokaryotes.

What is the function of a regulatory gene?

It produces a repressor protein that can block transcription of an operon.

What is natural selection's role in mutation?

Mutations may enhance the survival of an organism and can be subject to natural selection.

What is gel electrophoresis used for?

To separate DNA fragments by size.

What does PCR stand for, and what is its purpose?

Polymerase Chain Reaction; it's used to make multiple copies of a specific DNA segment.

What is DNA sequencing?

The process of determining the order of nucleotides in DNA.

What is the impact of chromatin structure on gene expression?

Tightly wound DNA is less accessible for transcription, impacting gene expression.

What are cytoplasmic determinants?

Substances in the maternal egg that influence early cellular development and differentiation.

What is apoptosis and its significance in development?

Apoptosis is programmed cell death that shapes developing organisms by removing unnecessary cells.

How do mutations affect phenotype?

Mutations can change genetic material, altering phenotypes and potentially leading to new traits.

What are point mutations?

Changes in a single nucleotide pair of a gene.

What are some examples of large scale mutations?

Nondisjunction, translocation, inversions, duplications, and deletions of chromosome segments.