Campbell Biology DNA, Cell Cycle, and Genetics Study Guide

Flashcards covering DNA structure, replication, cell cycle checkpoints, mitosis versus meiosis, genetics, and biotechnology based on the Campbell Biology study guide.

Why is complementary base pairing essential for replication?

It ensures accurate copying of the DNA molecule.

What happens if a mutation alters DNA polymerase?

Errors in DNA replication increase because the polymerase's ability to build accurately is compromised.

Why are checkpoints important in the cell cycle?

They act as a safety system to prevent damaged DNA from being passed on to daughter cells.

What does the observation that abnormal cells do not always become cancer suggest about the cell cycle?

It suggests that cell cycle checkpoints are effectively controlling and regulating the cells.

Why does meiosis produce genetic variation unlike mitosis?

Variation is produced due to the process of crossing over.

Why is sexual reproduction considered advantageous for a species?

The variation it creates improves survival chances for the population.

Why are the effects of sex chromosome nondisjunction generally less severe than those of autosomes?

Only one X chromosome is active in cells and the Y chromosome is relatively small.

What is the term for the flow of genetic information from DNA to RNA to Protein?

Gene expression

If a specific gene is not expressed in a cell, what is a likely molecular cause?

The absence of a necessary transcription factor.

How can two heterozygous parents produce a child with a recessive phenotype?

Both parents must have passed a recessive allele to the child.

Why do polygenic traits show a wide range of variation?

Because they are controlled by many genes rather than a single gene.

What materials are required to create recombinant DNA?

A vector and the target DNA sequence.

Why do scientists compare human and chimpanzee genomes?

To study and understand evolution.

Which specific enzyme is responsible for unzipping the DNA double helix?

Helicase

In what direction is DNA always built?

$$5' \rightarrow 3'$$

During which phase of the cell cycle is DNA replicated?

The S phase

What is the name of the structure that pinches an animal cell during cytokinesis?

Cleavage furrow

What is the direct consequence if tRNA (transfer RNA) fails to function?

No protein can be produced by the cell.

What occurs if a cell cycle checkpoint fails to stop a defective cell?

It can lead to the development of cancer.

Q1: A study finds that only a small percentage of individuals with a certain mutation develop

cancer. What is the BEST explanation?

B) Cancer always requires multiple mutations

Researchers find that some cells with damaged DNA do not become cancerous. Why?

C) Checkpoints detect and eliminate damaged

cells

A drug reduces activity of transcription factors. What is the MOST likely outcome?

B) Many genes are not expressed ■

: In a population, individuals with more genetic variation survive environmental change better. Why?

C) Variation increases chance of favorable

traits

Scientists observe that organisms with sexual reproduction adapt faster to

environmental change. Why?

B) Crossing over and independent assortment increase variation

A cell shows double DNA but has not divided yet. Which phase is it MOST likely in?

G2

: A study finds that a mutation in tRNA leads to defective proteins. What does this indicate?

e B) Amino acids are incorrectly delivered