BIO 14 LEC: Cell Cycle and Division

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Questions and Answers

What is the primary role of messenger RNA (mRNA) in protein synthesis?

Forms amino acids

Translates codon sequences

Carries code out of nucleus to ribosomes (correct)

Facilitates base pairing in ribosomes

What type of mutation results in a single base change in a DNA sequence?

Chromosome mutation

Missense mutation

Frameshift mutation

Point mutation (correct)

Which mutation alters a codon to a stop codon, potentially terminating protein synthesis early?

Missense mutation

Nonsense mutation (correct)

Insertion mutation

Silent mutation

Which of the following statements regarding the genetic code is true?

AUG is both a start codon and codes for an amino acid. Signup and view all the answers

What type of mutation causes significant changes to the reading frame by inserting or deleting base pairs?

Frameshift mutation Signup and view all the answers

Which type of stem cell is characterized by the ability to differentiate into multiple cell types?

Multipotent stem cells Signup and view all the answers

What type of meristem is responsible for increasing the girth of a plant?

Lateral meristem Signup and view all the answers

Which types of tissue do protoderm, ground meristem, and procambium produce?

Dermal, vascular, and ground tissues respectively Signup and view all the answers

Where is DNA found in prokaryotic cells?

Free-floating within the cytoplasm Signup and view all the answers

Which type of nucleic acid is primarily involved in protein synthesis?

RNA Signup and view all the answers

What is the primary function of the cork cambium in plants?

Produce periderm and secondary dermal tissue Signup and view all the answers

Which of the following accurately describes the function of intercalary meristems?

Elongate stems from the middle, between nodes Signup and view all the answers

What are nucleotides comprised of?

Sugar, base, and phosphate group Signup and view all the answers

What structure does the vascular cambium give rise to during secondary growth?

Secondary xylem Signup and view all the answers

Which of the following statements is true about totipotent stem cells?

Able to differentiate into any tissue type only in early development Signup and view all the answers

What is the primary role of RNA polymerases during transcription?

To synthesize RNA copies of genes in a 5’ to 3’ direction Signup and view all the answers

Which part of the DNA is known as the +1 site?

The first nucleotide pair where RNA transcription begins Signup and view all the answers

What feature characterizes the initiation complex in eukaryotic transcription?

It comprises both transcription factors and RNA polymerase Signup and view all the answers

How does Rho-dependent termination of transcription occur?

By the rho protein colliding with RNA polymerase Signup and view all the answers

What is the primary difference between Rho-dependent and Rho-independent termination in prokaryotes?

Rho-dependent requires rho protein while Rho-independent utilizes RNA sequences Signup and view all the answers

Which sequence element acts as a key binding site for RNA polymerase in prokaryotic transcription?

The consensus sequence located at -35 Signup and view all the answers

During transcription elongation, RNA polymerase synthesizes mRNA at a rate of how many nucleotides per second?

40 nucleotides per second Signup and view all the answers

What ensures that transcription begins at the correct site on the DNA?

Promoter sequences located upstream of the gene Signup and view all the answers

What sugar component is found in RNA but not in DNA?

Ribose Signup and view all the answers

Which nitrogenous bases are classified as purines?

Adenine and Guanine Signup and view all the answers

In DNA, what is the significance of the 5' to 3' directionality?

It indicates the site of phosphate group attachment. Signup and view all the answers

What type of bond links the nitrogenous bases in the DNA double helix?

Hydrogen bonds Signup and view all the answers

Which of the following statements about nucleosomes is true?

They consist of DNA wrapped around histones. Signup and view all the answers

What is the role of DNA gyrase in prokaryotic cells?

It helps maintain the supercoiled structure of DNA. Signup and view all the answers

During protein synthesis, what does a codon represent?

A sequence of three nucleotides Signup and view all the answers

What is the main function of the sugar-phosphate backbone in DNA?

To provide structural support and integrity Signup and view all the answers

What are the complementary nitrogen base pairings in DNA?

AT and GC Signup and view all the answers

What differentiates heterochromatin from euchromatin?

Heterochromatin is less dense and active. Signup and view all the answers

What is the primary purpose of the cell cycle?

To manage cellular growth, DNA synthesis, and division Signup and view all the answers

Which phase of the eukaryotic cell cycle includes DNA replication?

S Phase Signup and view all the answers

What is the role of checkpoints in the cell cycle?

To ensure proper completion of phases before progressing Signup and view all the answers

What occurs during prophase in mitosis?

Nuclear envelope breaks down and chromatin condenses Signup and view all the answers

How do plant cells divide differently from animal cells during cytokinesis?

They form a cell plate. Signup and view all the answers

What initiates the G0 phase for a cell?

The cell fails to reach the size requirement during G1 checkpoint Signup and view all the answers

Which statement accurately describes the process of meiosis?

It produces four haploid cells. Signup and view all the answers

What happens during anaphase of mitosis?

Sister chromatids are separated and pulled to opposite sides. Signup and view all the answers

What can happen if the cell cycle is not properly regulated?

Cancers may develop from uncontrolled cell division. Signup and view all the answers

Which of the following occurs during metaphase I of meiosis?

Homologous chromosomes pair and align at the equator. Signup and view all the answers

What is produced during the S phase of the cell cycle?

Sister chromatids Signup and view all the answers

Which phase follows telophase in the cell division process?

Cytokinesis Signup and view all the answers

What defines a zygote in biological terms?

A single cell formed from fertilization Signup and view all the answers

What is a key difference between prokaryotic and eukaryotic cell division?

Eukaryotic cells have multiple chromosomes and a nucleus. Signup and view all the answers

Study Notes

Cell Division and Cell Cycle

Cell division involves a parent cell splitting into two daughter cells.
Prokaryotic cells have simpler division compared to eukaryotic cells.
- Prokaryotes: one circular chromosome, no nucleus, minimal organelles.
- Eukaryotes: multiple chromosomes, nucleus with organelles.
The cell cycle consists of repeating events of growth, DNA synthesis, and division.

Eukaryotic Cell Cycle Phases

Mitotic Phase (M): Consists of mitosis and cytokinesis, where the nucleus and cytoplasm divide.
Interphase: Contains G1, S, and G2 phases.
- Growth Phase 1 (G1): Cell primarily grows and performs routine functions; high metabolic activity; if not dividing, enters G0 phase.
- Synthesis Phase (S): DNA replication occurs, resulting in sister chromatids; centrosomes duplicate and form mitotic spindle.
- Growth Phase 2 (G2): Short growth phase focused on producing organelles and replenishing energy stores.

Mitosis Process

Mitosis is multi-phased, involving chromosome sorting and separation.
Prophase: Chromosomes condense, nucleolus and nuclear envelope disappear, centrosomes migrate, and the mitotic spindle forms.
Metaphase: Chromosomes align at the metaphase plate; spindle fibers prepare to separate chromatids.
Anaphase: Sister chromatids separate, moving towards opposite poles, ensuring identical genetic material in daughter cells.
Telophase: Nuclear membranes reform, mitotic spindle disassembles; cell prepares to split.
Cytokinesis: Division of cytoplasm; in animal cells, a contractile ring forms; in plant cells, a cell plate is established.

Cell Cycle Regulation

Regulatory proteins control the cell cycle, ensuring phases are completed before progression.
Key checkpoints:
- G1 checkpoint: Assesses cell size; if inadequate, the cell enters G0.
- S Phase checkpoint: Confirms proper DNA replication.
- Mitosis checkpoint: Ensures chromosomes are correctly aligned before division.

Cancer and the Cell Cycle

Cancer results from unregulated cell cycle due to damaged DNA and mutations in regulatory genes.
Rapid division leads to tumor formation; cancer cells consume resources and can damage organs.
HeLa cells, derived from Henrietta Lacks, exemplify immortalized cells used in research.

Meiosis Overview

Meiosis is the process producing haploid cells with half the chromosome number through two stages: Meiosis I and II.
Meiosis I: Homologous chromosomes pair and undergo crossing-over; results in two haploid daughter cells.
Meiosis II: Equational division where sister chromatids separate, forming four haploid cells.

Cellular Differentiation and Development

Development begins with a zygote; different cell types arise as the organism grows.
Stem cells retain the ability to differentiate into various cell types through asymmetric division.

Meristems in Plants

Meristems are centers for continuous cell division and growth.
- Apical Meristems: Located at shoot and root tips for primary growth.
- Lateral Meristems: Results in secondary growth, increasing girth (e.g., vascular cambium produces secondary tissues).
- Intercalary Meristems: Enable growth between nodes.

Central Dogma of Molecular Biology

DNA transcribes to mRNA, which translates to proteins.
Genetic code is universal; consists of codons (three-nucleotide sequences), where 64 combinations exist for 20 amino acids.
Mutations can be single base changes or frameshift mutations affecting genetic information.

Transcription Process

RNA polymerase synthesizes RNA from a DNA template.
Initiation: Promoters specify transcription start; TATA box plays a key role.
Elongation: mRNA synthesized in the 5' to 3' direction.
Termination: In prokaryotes, transcription ends via rho-dependent or independent mechanisms.

RNA Types and Functions

mRNA: Carries genetic information from DNA to ribosomes for protein synthesis.
tRNA: Translates mRNA codons into corresponding amino acids.
rRNA: Structural RNA component of ribosomes, facilitating protein assembly.

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Description

This quiz covers the fundamental concepts of cell cycle and cell division in biology, specifically comparing prokaryotic and eukaryotic processes. It examines how a parent cell divides into two daughter cells and the duplication and separation of cell components. Perfect for students in the first semester of Biology of the Cell.