Mitosis Flashcards
Karyotype
A karyotype is an ordered, visual representation of the chromosomes in a cell.
Key Facts:
Used to examine chromosome number and structure.
Chromosomes are arranged by size and shape.
Humans have 46 chromosomes (23 pairs).
Includes autosomes (22 pairs) and sex chromosomes (XX or XY).
Sister Chromatids
Sister chromatids are identical copies of a chromosome, joined together at the centromere.
Key Facts:
Formed during DNA replication in S phase.
Separate during mitosis (anaphase) to ensure each new cell gets identical genetic material.
Each chromosome consists of two sister chromatids after replication.
Autosomes
Autosomes are non-sex chromosomes that determine most of an organism’s traits.
Humans have 22 pairs of autosomes.
The 23rd pair consists of sex chromosomes (X and Y).
Autosomal disorders occur when there is an abnormality in these chromosomes
Locus
A locus is the specific location of a gene on a chromosome.
Allele
An allele is an alternative version of a gene.
Diploid
A diploid cell (2n) contains two sets of chromosomes, one from each parent.
Key Facts:
Humans have 46 chromosomes (23 pairs).
Diploid cells are somatic cells (body cells).
The Cell Cycle
Definition:
The cell cycle is the series of events that cells go through to grow and divide.
Stages:
Interphase (most of the time spent here)
G1 phase: Cell growth and normal functions.
S phase: DNA replication occurs.
G2 phase: Preparation for mitosis.
Mitotic Phase: Mitosis and cytokinesis occur.
Mitosis
Mitosis is the process of cell division that produces two genetically identical daughter cells.
Key Phases:
Prophase - Chromosomes condense, spindle forms.
Metaphase - Chromosomes align in the center.
Anaphase - Sister chromatids separate.
Telophase - Nuclear envelope reforms.
Cytokinesis
Cytokinesis is the division of the cytoplasm to form two new cells.
Key Facts:
Occurs after mitosis.
In animal cells, a cleavage furrow forms.
In plant cells, a cell plate forms.
Centrosomes
Centrosomes are organelles that organize the mitotic spindle during cell division.
Key Facts:
Duplicate in interphase (G2 phase).
Help in chromosome movement during mitosis.
Mitotic Spindle
The mitotic spindle is a structure made of microtubules that helps separate chromosomes.
DNA Condensation
DNA condensation is the process of chromosomes becoming visible during mitosis.
Key Facts:
Occurs in prophase.
DNA wraps around histone proteins.
DNA Polymerase II
It is responsible for primer extension and proofreading.
DNA Polymerase III
It is responsible for in vivo DNA replication.
Helicase
Helicase is the enzyme, which unzips the DNA strands by breaking the hydrogen bonds between them. Thus, it helps in the formation of the replication fork.
Ligase
Ligase is the enzyme which joins together the Okazaki fragments of the discontinuous DNA strands.
Primase
This enzyme helps in the synthesis of RNA primer complementary to the DNA template strand.
Endonucleases
These produce a single-stranded or a double-stranded cut in a DNA molecule.
