Lecture 24 Flashcards
Define chromosomes
Threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
Define chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures.
Define Genome
Genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA
When and how does chromosome duplication happen?
Chromosome duplication occurs during the S phase of the cell cycle through DNA replication, producing identical sister chromatids connected by a centromere. This process leads up to cell division.
What are the cell cycle phases and what happens (including their relative timing)
G1 Phase:
Cell growth.
Variable duration.
S Phase:
DNA replication.
Follows G1.
G2 Phase:
Further growth and preparation.
Follows S phase.
M Phase (Mitosis):
Cell division.
Consists of prophase, metaphase, anaphase, and telophase.
Short duration.
What are the mitosis phases and what happens?
Prophase:
Chromosomes condense.
Nuclear envelope breaks down.
Spindle fibers form.
Metaphase:
Chromosomes align at the cell’s equator.
Spindle fibers attach.
Anaphase:
Sister chromatids separate.
Cell elongates.
Telophase:
Chromatids decondense.
Nuclear envelopes reform.
Spindle fibers disassemble.
Cytokinesis occurs.
What cytoskeleton components are involved in mitosis?
Microtubules:
Form the mitotic spindle, aiding in chromosome movement during mitosis.
Actin Filaments:
Participate in cytokinesis, facilitating the division of the cell into two daughter cells.
Describe the process and structures involved in cytokinesis?
Animal Cells:
Cleavage furrow forms.
Contractile ring of actin and myosin pinches the cell.
Two daughter cells are created.
Plant Cells:
Cell plate forms from vesicles.
New cell wall develops.
Two daughter cells are formed.
Where are the molecules controlling cell cycles located?
One near the end of G1, a second at the G2/M transition, and the third during metaphase.
