General Biology DNA Replication and Cell Cycle

Questions and Answers

What are the steps of DNA replication at the origin of replication?

DNA replication involves unzipping the double helix by helicase, creating a replication fork, synthesizing the leading strand continuously with a primer and DNA polymerase, and replicating the lagging strand discontinuously with multiple primers and Okazaki fragments.

What is semiconservative replication, and why is it significant?

Semiconservative replication is when each new DNA molecule consists of one original strand and one newly synthesized strand, reducing the probability of mutations during replication.

What is binary fission in prokaryotic organisms?

Binary fission is the process where an organism duplicates its DNA and then divides into two parts, with each new organism receiving one copy of DNA.

What are the stages of the cell cycle in a eukaryotic cell?

The stages of the cell cycle include G1 (growth), S (DNA synthesis), G2 (preparation for mitosis), and M (mitosis). Signup and view all the answers

What are the functions of mitosis in eukaryotic cells?

Mitosis is responsible for dividing the nucleus to produce two identical daughter cells, facilitating growth and cell renewal. Signup and view all the answers

What distinguishes chromatids, chromosomes, homologs, and sister chromatids?

A chromatid is a newly copied chromosome, a chromosome is a DNA molecule of genetic material, homologs are chromosomes with shared ancestry, and sister chromatids are identical copies of a chromosome joined by a centromere. Signup and view all the answers

What are the phases of mitosis, and what major events occur at each step?

The phases of mitosis include prophase, metaphase, anaphase, and telophase, where chromosomes condense, align, separate, and the cell divides respectively. Signup and view all the answers

What is the difference between haploid and diploid cells?

Haploid cells have one complete set of chromosomes, while diploid cells have two complete sets. Mitosis produces more diploid cells. Signup and view all the answers

Study Notes

DNA Replication

DNA replication involves copying DNA during cell division, initiated at the origin of replication.
Helicase enzyme unwinds the DNA double helix by breaking hydrogen bonds between base pairs, forming a replication fork.
Leading strand synthesized continuously with the help of an RNA primer made by primase and extended by DNA polymerase, which adds nucleotides in a 5' to 3' direction.
Lagging strand synthesized discontinuously through multiple RNA primers, forming Okazaki fragments, also extended in the 5' to 3' direction.
Exonuclease removes RNA primers; DNA polymerase fills gaps before DNA ligase seals and forms continuous double strands.
Results in two DNA molecules each consisting of one original and one new strand, termed semi-conservative replication.

Semiconservative Replication

Semiconservative replication ensures each new DNA strand includes one original and one newly synthesized strand.
This mechanism significantly reduces mutation rates due to the presence of an accurate template.

Binary Fission

Binary fission is the primary reproduction method for prokaryotic organisms, involving duplication of genetic material followed by division.
Each new organism receives one copy of the DNA, resulting in two genetically identical cells.

Stages of the Cell Cycle in Eukaryotic Cells

The cell cycle comprises several stages: Interphase (G1, S, G2) and M phase (mitosis and cytokinesis).
G1 phase focuses on cell growth, S phase involves DNA synthesis, and G2 phase prepares for mitosis by producing necessary proteins and organelles.
M phase includes mitosis (nuclear division) and cytokinesis (cytoplasmic division).

Functions of Mitosis

Mitosis facilitates cell division in eukaryotes, resulting in two identical daughter cells for growth and repair.
Prokaryotes reproduce via binary fission rather than mitosis due to the absence of a nuclear membrane.

Chromatids, Chromosomes, Homologs, and Sister Chromatids

Chromatids are newly copied chromosomes connected at the centromere; a chromosome contains one DNA molecule before replication.
Chromosomes are DNA structures containing genetic material, often condensed with packaging proteins.
Homologs share ancestry and can refer to similar chromosomes across different organisms.
Sister chromatids are identical copies of a chromosome formed during DNA replication, linked by a common centromere.

Animal Life Cycle

Life cycle connects fertilization (fusion of gametes) to zygote formation, followed by mitosis for growth and meiosis for producing gametes (haploid cells).

Phases of Mitosis

Mitosis phases (prophase, metaphase, anaphase, telophase) involve chromatin condensation, alignment of chromosomes, separation of sister chromatids, and reformation of the nuclear envelope.

Haploid vs. Diploid Cells

Diploid cells have two sets of chromosomes; haploid cells contain one set.
Mitosis produces diploid daughter cells from a diploid parent cell, ensuring genetic consistency.

Description

Explore the essential processes of DNA replication and cell division in this quiz on General Biology. Understand the steps involved at the origin of replication and the role of various enzymes, including helicase. This quiz is a valuable resource for mastering key biological concepts.