Flashcards in Chapter 8 - The Cellular Basis of Reproduction & Inheritance Deck (35):
What is cell division?
A way for cells to be able to reproduce themselves through either mitosis or meiosis.
What is asexual reproduction?
the production of a new individual that is genetically identical to the parent.
generally done through mitosis.
allows rapid population growth.
What is sexual reproduction?
the production of gametes which each have half the chromosome number of the parent producing them (are haploid).
gametes must fuse together who get a new individual that is not identical to the parent.
permits much more rapid population change through selection.
How do prokaryotes reproduce?
through binary fission and with DNA that is a single circular unit.
What are the qualities of a eukaryote chromosome?
single long DNA molecule bearing a linear sequence of genes with associated proteins.
Are chromosomes always paired in a eukaryote?
yes - meaning a diploid number of chromosomes...one from each parent.
what is the form of DNA during interphase?
dispersed throughout the nucleus.
what is DNA available for in the dispersed form?
transcription and as a template for DNA replication or chromosome duplication.
when does chromosome duplication take place?
during interphase, before the cell begins to divide.
What is chromosome duplication?
When the DNA within the nucleus duplicates itself in order for cell division and creation of two new cells.
Chromosome duplication in mitosis
daughter cells get a copy of each of the chromosomes that the parent cell has = 2n.
what is the cell cycle?
its when cells follow the regular cycle of growth & division.
what is interphase?
90% of the cell's lifespan and the "non-dividing" stage of the cell. this is the stage when the cell carries out normal metabolic activities.
what are the 3 subphases of interphase?
G1: mainly growth, maintenance, specialized functions.
G2: continued growth, DNA replication.
G3: continued growth and preparation for cell division.
what is the mitotic phase?
the stage when the sister chromatids divide at the centromere and begin moving towards opposite sides of the dividing cell = 2 new genomes within cell but still diploid.
what is cytokinesis?
cytoplasm divides, two new cells formed, each with its own full set of chromosomes.
What happens during prophase?
nucleus: chromosomes condense, become visible as sister chromatids.
cytoplasm: centromeres divide and begin separating; mitotic spindle microtubules begin forming between them.
what happens during prometaphase?
nucleus: nuclear envelope disappears, sister chromatids become attached to spindle microtubules, and sister chromatids begin to move towards central plane of cell.
cytoplasm: centromeres more to opposite poles of the cell and spindle microtubules establish spindle spanning cell.
what happens during metaphase?
nucleus: no longer present.
cytoplasm: chromosomes fixed to spindle microtubules, centromeres align along metaphase plane.
what happens during anaphase?
cytoplasm: sister chromatids aligned at the metaphase plane split apart at centromeres, begin moving towards opposite poles of the cell. Unoccupied spindle microtubules elongate, cell elongates between poles.
what happens during telophase?
begins after arrival of all chromosomes at opposite poles of parent cell.
nucleus: nuclear membrane reestablished for each daughter cell. chromosomes disperse from condensed form.
cytoplasm: elongation between poles of parent cell continues. mitotic spindle disappears. cytokinesis begins.
what happens during cytokinesis?
in animals, cleavage furrow forms between daughter cells - function of cytoskeletal actin interacting with myosin to form contracting ring, pinching parent cell in two.
in plants, cellulose cell wall forms between daughter cells and separates them from one another.
what is the system that controls the cell cycle?
A endogenous cell cycle assesses process up to that point of each checkpoint, if status satisfactory, process allowed to proceed.
checkpoints also allow external signals to influence cell cycle (growth factors).
what are cell growth factors are what are their roles?
Cell membrane generally impermeable to growth factors; receptors specifically for an given growth factor must be present on surface of the cell.
Bonding of growth with specific receptor on surface
what is meiosis?
essentially like mitosis, but instead of duplicated 2 cells that result in identical daughter cells, meiosis results in 4 daughter cells that are haploid and genetically different from the parent cell that created them.
what is an important aspect of meiosis 1?
results in a reduction division...chromosomes divide among the 2 daughter cells in homologous pairs. meaning, chromosomes between the 2 cells have been halved that of what was in the parent cell.
what are tetrads?
tetrads are when 2 chromosomes pair up with each along the metaphase plane and then split between the 2 daughter cells...resulting in 2 haploid daughter cells.
what is a gene?
a locus on a chromosome or a length of DNA coding for a specific protein.
what are alleles?
a version of a gene, having a variant of the base sequence which produces a different version of the same protein coded for any other versions (alleles) of that gene.
what is independent assortment?
it is when the tetrad pair line up along the midline plane of the dividing cell and which side the chromosomes end up on. it is independent for each tetrad pair of chromosomes and results in daughter cell be able to have different combinations of paternal and maternal chromosomes.
what is crossing over?
during metaphase 1 when corresponding sections can be swapped between maternal and paternal versions of the chromosomes.
this produces new combinations of alleles not seen in either parent.
chromosomes produced by crossing ver in meiosis and bearing new combinations of parental alleles.
produces dissimilar gametes.
what is a karyotype?
a karyotype is the number and morphology of the chromosomes, specific to a species.
what are non-disjunctions?
failure in separation between homologous pairs in metaphase 1 or 2.