Chapter 2: Reproduction Flashcards
Diploid:
(2n), 2 copies of each chromosome. • Animals have this. • Autosomal.
Haploid:
(n), 1 copy of each chromosome. • Germ cells have this.
Eukaryotic Cells:
Replicate through the cell cycle.
Cell Cycle:
This is a series of phases during which a cell grows, synthesizes DNA, and divides. Consists of 4 stages. G1, S, G2, and M
Interphase: G1, S, & G2
Longest part of the cycle Spends 90% of time dividing here DNA is available to RNA polymerase so genes can be transcribed.
G0 stage:
In this stage, cells are simply living and serves its functions without any preparation for division.
G1 Stage: AKA Presynaptic Gap.
In this stage, cells create organelles for energy and protein production, and also increases their sizes. ○ Organelles like mitochondria, ribosomes, and ER. ○ Has a restriction point. § Controls the passage into the S-stage.
S-Stage:
In this stage, cells replicate its genetic material so each daughter cells will have identical copies. ○ After replication, each chromosomes consists of 2 identical chromatids that are stuck together in a section called centromere.
G2-stage:
In this stage, cells pass through a quality checkpoint. ○ DNA has already been duplicated. ○ Cells check to ensure that there’s enough organelles and cytoplasm to divide between 2 daughter cells. ○ Cells checks to make sure DNA replication proceeds correctly. § Avoids passing error to daughter cells. § Called G2/M Checkpoint § Has a p53 protein.
Other Checkpoints:
○ G1/S Checkpoint: Cell determines if the DNA is good enough condition for synthesis. § AKA Restriction point. § P53 protein is the main protein in control.
M-Stage:
Mitosis and Cytokinesis.
Mitosis:
This is a process by which two identical daughter cells are created from a single cell. • Occurs in somatic cells. • Has 4 phases (prophase, metaphase, anaphase, telophase)
Somatic Cells?
Cells that are not involved in sexual reproduction.
Prophase:
Condensation of chromatin into chromosomes. In this phase, the centriole pairs will separate and move toward opposite poles of the cell, which will form spindle fibers, that are made from microtubles. The nuclear membrane and the nuclei will dissolve and the kinetochores will come in.
Kinetochores?
These are protein structures that are located on the centromeres that serves as attachment points for kinetochore fibers.
Metaphase:
In this phase, centriole pairs are on opposite ends of the cell. Here, the kinetochore fibers interact with fibers of the spindle apparatus to align the chromosomes at the metaphase plate.
Anaphase:
In this phase, the centromeres split so that each chromatid has its owns distinct centromere, which allows sister chromatids to separate. Here sister chromatids are pulled towards opposite poles which shortens kinetochore fibers.
Telophase:
This phase is the reverse of prophase, where the spindle apparatus disappears, and the nuclear membranes reform, and nucleoli reappears.
Cytokinesis:
This phase is the separation of the cytoplasm and organelles so that each daughter cells has sufficient supplies and survive on its own. This will create 2 daughter cells that are identical.
Meiosis:
Occurs in gametocytes (germ cells) and results in 4 non-identical sex cells (gametes). • Two Types of Meiosis: Meiosis 1 & 2.
How is Meiosis similar to mitosis:
It is similar by genetic material gets duplicated, chromatin gets condensed to form chromosomes.
How is meiosis different than mitosis:
It is different because mitosis has 1 replication and 1 division, while meiosis has 1 replication and 2 divisions.
Meiosis 1:
Results in homologous chromosomes being separated, generating haploid daughter cells aka reduction division. ○ Has 4 phases (prophase 1, metaphase 1, anaphase 1, and telophase 1)
Meiosis 1 (Prophase 1):
In this, the chromatin condenses into chromosomes, the spindle apparatus forms, the nucleoli and nuclear membrane disappears. In this synapsis and chiasma takes place.
