Chapter 2 Flashcards
Prokaryote
A cell that lacks a cellular membrane and doesn’t possess membrane-bound organelles
Eukaryote
A complex cell that contains a nucleus and membrane-bound organelles
Nucleus
Located in eukaryotes. It separates the DNA from other cellular contents
Histone
A special class of proteins. They limit enzymes and proteins that copy/read DNA but they allow the DNA to fit into the nucleus. The DNA must separate from the histones before the genetic information can be accessed.
Chromatin
Made up of DNA and histones. Chromatin makes up chromosomes.
Homologous pair
A pair of chromosomes that are alike in size, structure, and carry information for the same chromosomes. They aren’t necessarily identical.
Ex: may both code for hair color, but may code for different colors
Diploid
Calls that carry two sets of genetic information
Haploid
Cells with a single set of chromosomes (only one copy of each gene).
Telomere
The natural ends of a linear chromosome. They protect and stabilize the ends of the chromosomes.
Centromere
The attachment point for the spindle micro tubules.
Origin of replication
The site where DNA synthesis begins.
Sister chromatid
Two initial identical copies after cell division. They a held together at the centromere
Cell cycle
The life of a cell. A new cycle begins after a cell has divided and produced 2 new cells. There are two main phases: Interphase and M phase.
Interphase
The period in between cell divisions in which the cell grows, develops, and functions.
M phase
Mitotic Phase. The period of active cell division.
Mitosis
The separation of chromosomes in the division of somatic (non-sex) cells (nuclear division).
Meiosis
The pairing and separation of chromosomes in the division of sex cells to produce gametes (reproductive cells). The chromosome number is reduced by half. It produces genetically variable cells.
Cytokinesis
Cytoplasmic division
Checkpoint
ensure that all cellular components are present and functional before moving on to the next stage. Defects in checkpoints can lead to unregulated cell growth.
Prophase
Contains two chromatids attached at the centromere; mitotic spindle forms; chromosomes condense
Metaphase
chromosomes line up on the metaphase plate; centrosomes go to the opposite ends of the cell and align chromosomes; no nuclear membrane at this point
Anaphase
Sister chromatids separate and move towards opposite centrosomes; now there is a total of 8 chromosomes
Telophase
chromosomes arrive at spindle poles; the nuclear membrane reforms and the chromosomes relax; 4 chromosomes in each daughter cell. 2N=4
Gametogenesis
?
Fertilization
Two haploid gametes fuse and restore chromosome number to it’s original diploid value.
Prophase I
chromosomes contract and become visible (leptotene); chromosomes continue to condense (zygotene); chromosomes become shorted and thicker (pachytene); homologous chromosomes exchange genetic information (crossing over)
Synapsis
pairs the homologous chromosomes; creates a tetrad
Bivalent
four chromatids (a.k.a tetrad)
Tetrad
Four chromatids (a.k.a bivalent)
Crossing Over
When homologous chromosomes exchange genetic information. It generates genetic variation and is essential for the proper alignment and separation of homologous chromosomes.
Metaphase I
When homologous pairs of chromosomes line up on the metaphase plate. Can NOT be somatic cells.
Anaphase I
The 2 chromosomes (each containing 2 chromatids) of each homologous pair separate and move toward opposite poles. Diads.
Telophase I
Chromosomes arrive at spindle poles and the cytoplasm divides. N=2, haploid cells.
Interkinesis
The period between meiosis I and meiosis II. The nuclear membrane re-forms around the chromosomes at each pole, the spindle breaks down, and the chromosomes relax.
Prophase II
The chromosomes (now diads) re-condense. There is one set of chromosomes in each daughter cell.
Metaphase II
Individual chromosomes line up on the equatorial plate.
Anaphase II
Sister chromatids separate and move toward opposite poles.
Telophase II
Chromosomes arrive at the spindle poles and the cytoplasm divides. N=2.
Recombination
Creating new combinations of alleles on a chromatid. Produces genetic variation.
Cohesion
A protein that holds the chromatids together in the S phase, G2 phase, and early mitosis.
Spermatogenesis
The production of gametes in a male animal. Takes place in the testes. Diploid germ cells divide mitotically to produce diploid cells called spermatogonia.
Oogenesis
The production of gametes in a female animal. Diploid germ cells divide mitotically to produce oogonia.
Oocyte
Diploid cells. (?)
