AP Biology - Chapters 16-18 Flashcards

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Questions and Answers

Which scientific claim is most consistent with the findings that transcription of gene R decreases when histone methyltransferase activity is inhibited?

Histone methylation condenses the chromatin at gene R so transcription factors cannot bind to DNA. (correct)

Histone methylation has no effect on transcription of gene R.

Histone methylation promotes accessibility of transcription factors.

Histone methylation increases transcription of gene R.

Which of the following is most likely responsible for the seasonal change in coat color in arctic foxes?

Exposure to sunlight enhances coat color.

Lower temperature in winter denatures the pigment molecules. (correct)

Higher temperatures increase pigment production.

Diet changes affect fur color.

At what stage of protein synthesis can gene expression be controlled?

All of the stages except protein folding.

Structural genes are genes that code for the production of _____.

rRNA, tRNA, and mRNA molecules. Signup and view all the answers

A sequence of CCT on a DNA molecule will ultimately match to the sequence of an anticodon and the triplet code for codon.

CCU // GGA Signup and view all the answers

What is the function of a restriction enzyme?

Cuts DNA molecules at specific locations to protect bacterial cells from foreign DNA. Signup and view all the answers

What is a cloning vector?

A tool to transfer DNA into plasmids. Signup and view all the answers

Where are restriction enzymes found?

In bacteria. Signup and view all the answers

What are sticky ends?

Tails of free DNA bases on cut DNA. Signup and view all the answers

What is a dideoxynucleotide?

Inhibitor of DNA polymerase used for DNA sequencing. Signup and view all the answers

During replication, why are introns and exons kept and deleted?

Introns are removed from mRNA, and exons are joined together. Signup and view all the answers

What is splicing?

The removal of non-protein coding regions of RNA. Signup and view all the answers

What are GMOs?

Genetically modified organisms with inserted genes that change characteristics. Signup and view all the answers

What is gene linkage?

Genes located close together are inherited together. Signup and view all the answers

What is the function of structural genes?

Code for proteins needed for structure or function in the body. Signup and view all the answers

Why do complementary bases only pair with each other?

Consistent pairing allows accurate DNA replication and transcription. Signup and view all the answers

What is DNA replication?

The process of copying DNA during the cell cycle. Signup and view all the answers

What are the steps of transcription?

Poly binding, initiation, elongation, and termination. Signup and view all the answers

What occurs during transcription initiation?

RNA polymerase binds to the promoter region of a gene. Signup and view all the answers

What occurs during transcription elongation?

The RNA strand gets longer as new nucleotides are added. Signup and view all the answers

What happens during transcription termination?

RNA polymerase stops adding nucleotides and separates from the DNA. Signup and view all the answers

What is the final product of transcription?

The final product is pre-mRNA. Signup and view all the answers

What is translation?

The process by which a cell interprets a genetic message and builds a polypeptide. Signup and view all the answers

What occurs during translation initiation?

Small subunit binds to mRNA, initiator binds, large subunit binds. Signup and view all the answers

What happens during translation elongation?

tRNA brings over amino acids, forming peptide bonds as the ribosome moves. Signup and view all the answers

What triggers translation termination?

Triggered by stop codons. Signup and view all the answers

What is a polymerase?

An enzyme that synthesizes new DNA by adding nucleotides to a chain. Signup and view all the answers

What is helicase?

An enzyme that untwists the double helix at replication forks. Signup and view all the answers

What are single-strand binding proteins?

Proteins that help hold the DNA strands apart. Signup and view all the answers

What is topoisomerase?

An enzyme that relieves strain ahead of replication forks. Signup and view all the answers

What is primase?

An enzyme that synthesizes the RNA primer for DNA replication. Signup and view all the answers

What are the models for replication?

Semiconservative - each strand is half old and half new. (C) Signup and view all the answers

Steps of replication involve DNA ___ by breaking the hydrogen bonds between strands.

splits Signup and view all the answers

The leading strand is replicated continuously toward the replication fork in the ____ direction.

5' to 3' Signup and view all the answers

What is a primer?

A short RNA sequence added to DNA by primase. Signup and view all the answers

What is a lagging strand?

A strand that is replicated in short segments away from the replication fork. Signup and view all the answers

What are Okazaki fragments?

Short segments made on the lagging strand during DNA replication. Signup and view all the answers

What are telomeres?

Repeating units at the end of the DNA strand that protect DNA and serve as a 'clock.' Signup and view all the answers

What is the lac operon for?

Digesting lactose, working only when lactose is present. Signup and view all the answers

What is the trp operon?

Operon that makes tryptophan, inactive when tryptophan is present. Signup and view all the answers

Study Notes

Enzymes and Gene Regulation

Histone methyltransferases methylate specific amino acid sequences in histone proteins, influencing gene expression.
Inhibition of histone methyltransferase results in decreased transcription of gene R due to chromatin condensation.
Restriction enzymes cut DNA at specific sites, protecting bacteria from foreign DNA by fragmenting it.

Coat Color Adaptation

Arctic foxes change coat color with seasons; a white coat in winter and darker in summer.
Seasonal coat color changes result from lower winter temperatures denaturing pigment molecules.

Gene Expression and Protein Synthesis

Gene expression can be regulated at various stages except during protein folding.
Structural genes are responsible for coding rRNA, tRNA, and mRNA; essential for protein synthesis.
Different regions in DNA: introns (non-coding) and exons (coding for proteins). Introns are removed before mRNA exits the nucleus.

Transcription Process

Transcription consists of binding, initiation, elongation, and termination, resulting in the production of pre-mRNA.
RNA polymerase binds to the promoter, unwinding DNA for synthesis.
Elongation involves RNA polymerase adding nucleotides in a 3' to 5' direction.
Termination occurs when RNA polymerase reaches a specific sequence (TTATTT), detaching from the DNA.

Translation Overview

Translation is the process where RNA is converted into a polypeptide chain.
Initiation involves the small ribosomal subunit binding to mRNA and the assembly of the large ribosomal subunit.
Elongation involves tRNA bringing amino acids based on codon sequences, forming peptide bonds as ribosome moves.
Termination occurs when a stop codon is reached, triggering release factors to release the polypeptide.

DNA Replication and Repair

DNA replication creates identical copies, involving the enzymes: helicase (unzipping DNA), topoisomerase (relieving strain), and primase (synthesizing RNA primers).
Leading strand is synthesized continuously towards the replication fork while the lagging strand is synthesized discontinuously as Okazaki fragments.
Telomeres protect DNA ends from degradation and help regulate cell division cycles.

Operon Functionality

The lac operon functions for lactose digestion and is induced by lactose presence; a repressor blocks operon when lactose is absent.
The trp operon synthesizes tryptophan; in its absence, the operon is active, while tryptophan presence inactivates it.

Cloning and Genetic Engineering

Cloning vectors facilitate DNA insertion into plasmids.
Sticky ends produced by restriction enzymes enable the joining of DNA fragments during cloning.
GMOs are organisms with modified genes to alter specific traits.

Key Terms

Dideoxynucleotides inhibit DNA polymerase and are used in DNA sequencing.
Splicing is the removal of introns from pre-mRNA, joining exons to form mature mRNA.

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Prepare for your AP Biology exam with these flashcards covering key concepts from chapters 16 to 18. These cards will help you understand critical topics such as histone methyltransferases and their role in gene transcription. Test your knowledge and boost your retention with this focused study aid.