L4: CELL DIVISON Flashcards
Why do cells divide in our body?
Cells divide for growth and development, to maintain and replace tissues, and to pass on genetic information.
What are the main stages of cell division?
The main stages are Interphase and Mitosis/Meiosis
What type of cells undergo mitosis?
Cells that make up the body but are not involved in sexual reproduction undergo mitosis.
Which cells in the body undergo meiosis?
Meiosis occurs exclusively in cells that produce sperm and eggs.
Can you give an example of mitosis in the body?
Skin turnover is an example of mitosis.
What happens during mitosis?
A single parent cell divides into two identical daughter cells, each with a full set of DNA and organelles.
What are the two main stages of the cell cycle?
The two main stages are Interphase and Mitosis (or cell division).
What are the phases of Interphase?
Interphase consists of three phases: G1 (cell growth), S (DNA replication), and G2 (preparation for mitosis).
What happens during the G1 phase?
During G1, the cell grows and produces proteins needed for DNA replication in the S phase.
What happens during the G2 phase?
In G2, the cell prepares for mitosis by synthesizing proteins required for division.
What is chromatin?
Chromatin is DNA wrapped around proteins in the nucleus, which condenses into chromosomes during mitosis.
What is a chromosome?
A chromosome is a single strand of DNA that becomes condensed and visible during mitosis.
What happens during prophase?
DNA condenses into chromosomes, centrosomes move to opposite poles, and spindle fibers begin to form.
What happens during late prophase?
The nuclear envelope dissolves, and spindle fibers attach to chromosomes at the kinetochore.
What happens during metaphase?
During metaphase, chromosomes align at the metaphase plate in the center of the cell.
What happens during anaphase?
In anaphase, sister chromatids are pulled to opposite poles of the cell, becoming daughter chromosomes.
What happens during telophase?
In telophase, chromosomes de-condense, new nuclei form, and the spindle breaks down.
What happens during cytokinesis?
Cytokinesis is the final step of cell division, where the cytoplasm splits, and two daughter cells are formed. In animal cells, a cleavage furrow forms.
How many chromosomes do humans have?
Humans have 46 chromosomes, which are arranged in 23 pairs
Why do we say humans have 23 pairs of chromosomes?
Humans inherit 23 chromosomes from their father and 23 chromosomes from their mother, forming 23 homologous pairs.
How are gametes (sperm and egg) different from somatic cells?
Gametes are haploid, meaning they have only 23 chromosomes, half the number of chromosomes in somatic (body) cells.
What is meiosis?
Meiosis is the process by which gametes (sperm and eggs) are produced, halving the chromosome number from diploid to haploid.
What happens during Meiosis I?
In Meiosis I, homologous chromosomes pair up and are separated into different cells, resulting in haploid daughter cells.
What happens during Meiosis II?
Meiosis II is similar to mitosis, where chromatids separate, resulting in four haploid gametes.
What is fertilization?
Fertilization is the fusion of a sperm and egg (both haploid), resulting in a zygote with a diploid chromosome number.
