AP BIO

What is the backbone of DNA made of?

The backbone of DNA is made of sugar (deoxyribose) and phosphate groups.

What are the steps of the DNA ladder?

The steps of the DNA ladder are made of nitrogenous bases.

What term describes nitrogenous bases with 2 rings?

They are called purines, which include adenine (A) and guanine (G).

What term describes nitrogenous bases with 1 ring?

They are called pyrimidines, which include cytosine (C) and thymine (T).

What are the base pair rules and what bond holds them together?

The base pair rules are A pairs with T, and C pairs with G; hydrogen bonds hold them together.

What part of the backbone do the bases bond to? What type of bonds hold the backbone together?

The nitrogenous bases bond to the sugar in the backbone, which is held together by phosphodiester bonds.

Describe the antiparallel arrangement of DNA.

In DNA, one strand runs in the 5' to 3' direction while the other runs in the 3' to 5' direction.

Why is the replication of DNA called a semiconservative model?

Because each new DNA molecule contains one original strand and one newly synthesized strand.

Describe the function of helicase and topoisomerase.

Helicase unwinds the DNA double helix, while topoisomerase alleviates strain ahead of the replication fork.

Describe the function of primase.

Primase synthesizes a short RNA primer using RNA nucleotides to initiate DNA replication.

Describe the function of the RNA primers.

RNA primers provide a starting point for DNA polymerase to begin synthesizing new DNA strands.

Describe the functions of DNA polymerase.

DNA polymerase reads the template strand in a 3' to 5' direction and builds the new strand in a 5' to 3' direction.

Describe the function of DNA ligase.

DNA ligase joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.

Differentiate between the leading strand and lagging strand.

The leading strand is synthesized continuously while the lagging strand is synthesized in short fragments called Okazaki fragments.

Describe the problem with replication of the 5’ ends of a linear DNA molecule.

The replication process cannot fully replicate the 5’ ends, leading to progressive shortening of chromosomes.

Define a telomere.

A telomere is a repetitive nucleotide sequence at the ends of linear chromosomes that protects them from degradation.

What is the job of telomerase?

Telomerase adds repetitive sequences to the ends of chromosomes to maintain their length during replication.

What happens to your DNA over time?

Over time, DNA can undergo shortening and damage, which contributes to aging; this does not happen in cancer cells due to their ability to maintain telomere length.

Define transcription.

Transcription is the process of synthesizing RNA from a DNA template.

Define translation.

Translation is the process of synthesizing proteins from an mRNA template.

Why are transcription and translation separated in eukaryotes?

In eukaryotes, transcription occurs in the nucleus and translation occurs in the cytoplasm, allowing for RNA processing and regulation.

What are the differences between DNA and RNA?

DNA contains deoxyribose sugar and is double-stranded, while RNA contains ribose sugar and is single-stranded.

What term describes the DNA sequence where RNA polymerase attaches?

The DNA sequence is called a promoter.

What sequence/nucleotides are common in eukaryotic promoters?

Common sequences in eukaryotic promoters include the TATA box.

What is the purpose of the 5’ cap and poly A tail in RNA processing?

The 5’ cap and poly A tail protect mRNA from degradation and facilitate its export from the nucleus.

Explain eukaryotes and RNA splicing (introns vs. exons).

RNA splicing removes non-coding regions (introns) and joins coding regions (exons) in eukaryotic mRNA.

What are snRNPs/spliceosomes? What do they do?

SnRNPs are small nuclear ribonucleoproteins that, together as spliceosomes, catalyze the splicing of pre-mRNA.

Define a codon.

A codon is a sequence of three nucleotides in mRNA that specifies a particular amino acid.

What is tRNA? What does it do?

tRNA (transfer RNA) is a molecule that carries amino acids to the ribosome during protein synthesis.

Describe the structure of the ribosome.

The ribosome consists of two subunits (large and small) and has three sites: P site, A site, and E site.

Describe initiation of translation.

Translation always starts at the start codon (AUG) on the mRNA.

Describe elongation of translation.

During elongation, tRNA molecules bring amino acids to the ribosome, matching codons with anticodons.

Describe termination of translation.

Termination occurs when a stop codon is reached, signaling the end of protein synthesis.

Define polyribosomes.

Polyribosomes are clusters of ribosomes translating the same mRNA simultaneously.

Define mutation.

A mutation is a change in the DNA sequence of a gene.

Define point mutation.

A point mutation is a change in a single nucleotide base pair in DNA.

Define base pair substitution and possible results.

Base pair substitution replaces one nucleotide with another, potentially leading to silent, missense, or nonsense mutations.

Distinguish missense mutations from nonsense mutations.

Missense mutations result in a different amino acid, while nonsense mutations create a premature stop codon.

Describe a frameshift mutation.

A frameshift mutation occurs when nucleotides are added or deleted, altering the reading frame of the genetic code.

Define mutagen. Give an example.

A mutagen is an agent that causes mutations in DNA; an example is ultraviolet light.

Explain how mutations are overall neutral, but could be an advantage or disadvantage.

Mutations can be neutral with no effect on fitness, but some can provide advantages for survival or cause harmful effects.

Explain two LARGE Scale mutations through the process of nondisjunction.

Nondisjunction can lead to aneuploidy, such as Down syndrome (trisomy 21) or Turner syndrome (monosomy X).

What is a capsid?

A capsid is a protein shell that encloses the viral genome.

What is host range? Why is this normally a low number?

Host range is the spectrum of host cells that a virus can infect, usually low due to specific receptor interactions.

What does obligate parasites mean?

Obligate parasites can only reproduce within a host cell by using the host's cellular machinery.

Describe the lytic cycle.

The lytic cycle is a viral reproductive cycle that results in the lysis (death) of the host cell.

Describe the lysogenic cycle.

The lysogenic cycle allows viral DNA to integrate into the host's genome and replicate without killing the host.

What does reverse transcriptase do?

Reverse transcriptase converts viral RNA into DNA, allowing retroviruses to integrate into the host genome.

Can you use antibiotics on viruses?

No, antibiotics are ineffective against viruses.

Can you use vaccines on viruses?

Yes, vaccines can stimulate an immune response to viral infections.

Reproduce asexually by binary fission. All are clones of the original.

This process occurs in bacteria.

What is transformation in bacteria?

Transformation is the uptake of free DNA from the environment by a bacterial cell.

What is conjugation in bacteria?

Conjugation is the transfer of genetic material between bacteria through direct contact, often involving plasmids.

What is a plasmid?

A plasmid is a small, circular, self-replicating DNA molecule that exists independently from bacterial chromosomal DNA.

What is a repressible operon?

A repressible operon can be inhibited when a small molecule binds to a regulatory protein, like the trp operon.

What is an inducible operon?

An inducible operon can be stimulated when a small molecule binds to a regulatory protein, like the lac operon.

What are restriction enzymes?

Restriction enzymes cut DNA at specific sequences known as restriction sites.

What is PCR?

PCR (Polymerase Chain Reaction) is a technique used to amplify a specific DNA segment.

What is gel electrophoresis?

Gel electrophoresis is a method used to separate nucleic acids based on size and charge.