The Cell Life Cycle

Which proteins promote transcription?

a. Histone acetyltransferases

b. Transcription factors

c. Transcription co-repressors

d. DNA methyltransferases

Select all that apply

a,b Histone acetyltransferases turn transcription on and off by either adding or removing an acetyl group. Transcription factors bind with other proteins to induce transcription via DNA polymerase.

DNA is organized and condensed into _____ made of DNA and proteins like histones.

Chromosomes

It is not chromatin because chromatin is loose and the chromosomes are the wound/coiled chromatin.

What enzyme keeps DNA from becoming supercoiled during DNA replication?

a. helicase

b. DNA polymerase

c. topoisomerase

d. ligase

c. topoisomerase, it prevents supercoiling by untangling and unwinding the DNA

a. is incorrect because helicase "unzips" the DNA into single strands

b. is incorrect because DNA polymerase is used in replication

d. is incorrect because ligase is a "glue" between nucleic acids

What is the difference between a nucleotide and a nucleic acid?

A nucleotide is a single unit, while a nucleotide is a chain of multiple units

Site located at the beginning of a gene sequence where transcription is initiated.

a. intron

b. exon

c. promotor region

d. telomere

e. translation

c. promotor region

Non-coding segment of DNA that ultimately is removed from the mRNA sequence during splicing.

a. intron

b. exon

c. promotor region

d. telomere

e. translation

a. intron

Coding segment of DNA that ultimately becomes part of the mRNA sequence and the protein amino acid sequence during translation.

a. intron

b. exon

c. promotor region

d. telomere

e. translation

b. exon

Repetitive DNA sequence (TTAGGG) + specialized proteins that are located at the end of chromosomes.

a. intron

b. exon

c. promotor region

d. telomere

e. translation

d. telomere

The process of 'reading' the mRNA nucleotide order by ribosomes.

a. intron

b. exon

c. promotor region

d. telomere

e. translation

e. translation

______ is the enzyme responsible for 'spell checking' DNA replication

DNA polymerase

DNA replication occurs in the nucleus of eukaryotic cells.

True or False

True

Transcription is in the nucleus, translation occurs in the cytoplasm via ribosomes

What type of DNA damage is considered the most COMMON?

a. base substitutions

b. single strand breaks

c. deamination

d. double strand breaks

b. single strand breaks

What type of DNA damage is considered the most dramatic?

a. base substitutions

b. single strand breaks

c. deamination

d. double strand breaks

d. double strand breaks

Most cells in the body are dividing at a constant rate.

true or false

False, most cells are at rest and only divide when cellular production is necessary.

A nucleotide of DNA would contain:

a. deoxyribose, thymine, and a phosphate group

b. ribose, uracil, and a phosphate group

c. deoxyribose, uracil, and a phosphate group

d. ribose, thymine, and a phosphate group

a. deoxyribose, thymine, and a phosphate group

c. is incorrect because uracil is used by RNA

What is the correct order of cell cycle phases?

a. G1, G2, S, M

b. G1, M, G2, S

c. G1, S, M G2

d. G1, S, G2, M

d. G1, S, G2, M

Assign the cell cycle stages to the correct description of events

Cellular growth _____

DNA duplication ______

Cellular growth + reorganization ______

Duplicated genome + cytoplasmic structures segregated into two daughter cells ______

G1 - cellular growth

S - DNA duplication

G2 - cellular growth + reorganization

M - Duplicated genome + cytoplasmic structures segregated into two daughter cells

What are the different cell cycle checkpoints?

G1 - S transition

G2 - M transition

M

Intact (non-damaged) DNA, adequate cell growth, sufficient cell nutrients/macromolecules, appropriate materials for S phase and appropriate mitogenic signals are part of what checkpoint?

G1

Intact (appropriately duplicated) DNA is part of what checkpoint?

G2

Appropriate alignment of chromosomes (chromatid pairs) along the metaphase plate is part of what checkpoint?

M

The cell cycle is regulated by cyclins and cyclin-dependent kinases. Which description is correct?

a. Cyclin concentrations vary throughout the cell cycle due to transcriptional regulation; CDK concentrations also vary, so activity is transcriptionally regulated.

b. Cyclin concentrations vary throughout the cell cycle due to transcriptional regulation; CDK concentrations do not vary and activity is regulated by cyclin binding and appropriate phosphorylation signals.

c. Cyclin concentrations do not vary throughout the cell cycle thus activity is regulated by phosphorylation; CDK concentrations also do not vary and activity is regulated by cyclin binding and appropriate phosphorylation signals.

d. Cyclin concentrations do not vary throughout the cell cycle thus activity is regulated by phosphorylation; CDK concentrations do vary, so activity is transcriptionally regulated.

b. Cyclin concentrations vary throughout the cell cycle due to transcriptional regulation; CDK concentrations do not vary and activity is regulated by cyclin binding and appropriate phosphorylation signals.

Which scenarios more likely involves apoptosis as the major cellular death process?

a. A cat bites an electrical cord and burns a hole in its tongue.

b. A neutrophil (type of white blood cell) enters the bloodstream of a dog and dies when it is no longer needed.

c. The thymus (an organ that makes white blood cells) is large in a puppy but shrinks throughout its lifetime.

d. The skin webs between the fingers of a fetus regress prior to birth.

e. A tumor outgrows its blood supply, leading some areas of the tumor to lack blood supply.

b, c, d.

a, e are incorrect because those describe necrosis

Apoptosis is always a result of a normal physiologic process.

true or false

false, it can result from normal physiology or be secondary to a disease

What would be the most likely negative consequences of a cell being able to evade apoptosis?

a. zombies

b. immortality of the organism

c. unregulated cellular replication

d. more necrosis

e. replication of cells with DNA damages

c,e. unregulated cellular replication and replication of cells with DNA damages

Apoptosis is triggered by cytochrome C

true or false

true

Necrosis leaks cytochrome C which signals other cells to start what?

apoptosis