Chapter 8 - The Cellular Basis of Reproduction & Inheritance

Question 1

What is cell division?

Answer 1

A way for cells to be able to reproduce themselves through either mitosis or meiosis.

Question 2

What is asexual reproduction?

Answer 2

the production of a new individual that is genetically identical to the parent.
generally done through mitosis.
allows rapid population growth.

Question 3

What is sexual reproduction?

Answer 3

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.

Question 4

How do prokaryotes reproduce?

Answer 4

through binary fission and with DNA that is a single circular unit.

Question 5

What are the qualities of a eukaryote chromosome?

Answer 5

single long DNA molecule bearing a linear sequence of genes with associated proteins.

Question 6

Are chromosomes always paired in a eukaryote?

Answer 6

yes - meaning a diploid number of chromosomes…one from each parent.
Homologous chromosomes.

Question 7

what is the form of DNA during interphase?

Answer 7

dispersed throughout the nucleus.

Question 8

what is DNA available for in the dispersed form?

Answer 8

transcription and as a template for DNA replication or chromosome duplication.

Question 9

when does chromosome duplication take place?

Answer 9

during interphase, before the cell begins to divide.

Question 10

What is chromosome duplication?

Answer 10

When the DNA within the nucleus duplicates itself in order for cell division and creation of two new cells.

Question 11

Chromosome duplication in mitosis

Answer 11

daughter cells get a copy of each of the chromosomes that the parent cell has = 2n.

Question 12

what is the cell cycle?

Answer 12

its when cells follow the regular cycle of growth & division.

Question 13

what is interphase?

Answer 13

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.

Question 14

what are the 3 subphases of interphase?

Answer 14

G1: mainly growth, maintenance, specialized functions.
G2: continued growth, DNA replication.
G3: continued growth and preparation for cell division.

Question 15

what is the mitotic phase?

Answer 15

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.

Question 16

what is cytokinesis?

Answer 16

cytoplasm divides, two new cells formed, each with its own full set of chromosomes.

Question 17

What happens during prophase?

Answer 17

nucleus: chromosomes condense, become visible as sister chromatids.
cytoplasm: centromeres divide and begin separating; mitotic spindle microtubules begin forming between them.

Question 18

what happens during prometaphase?

Answer 18

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.

Question 19

what happens during metaphase?

Answer 19

nucleus: no longer present.
cytoplasm: chromosomes fixed to spindle microtubules, centromeres align along metaphase plane.

Question 20

what happens during anaphase?

Answer 20

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.

Question 21

what happens during telophase?

Answer 21

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.

Question 22

what happens during cytokinesis?

Answer 22

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.

Question 23

what is the system that controls the cell cycle?

Answer 23

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).

Question 24

what are cell growth factors are what are their roles?

Answer 24

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

Question 25

what is meiosis?

Answer 25

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.

Question 26

what is an important aspect of meiosis 1?

Answer 26

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.

Question 27

what are tetrads?

Answer 27

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.

Question 28

what is a gene?

Answer 28

a locus on a chromosome or a length of DNA coding for a specific protein.

Question 29

what are alleles?

Answer 29

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.

Question 30

what is independent assortment?

Answer 30

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.

Question 31

what is crossing over?

Answer 31

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.

Question 32

recombinant chromosomes

Answer 32

chromosomes produced by crossing ver in meiosis and bearing new combinations of parental alleles.
produces dissimilar gametes.

Question 33

what is a karyotype?

Answer 33

a karyotype is the number and morphology of the chromosomes, specific to a species.

Question 34

what are non-disjunctions?

Answer 34

failure in separation between homologous pairs in metaphase 1 or 2.

Question 35

Chromosome Rearrangements ~ can result in mutations

Answer 35

deletions: sections lost.
duplications: section lost from one homologue, inserted into sister homologue.
inversion: section lost, rotated and reinserted into same chromosome.
translocation: fragment lost from breakage becomes attached to non-homologous chromosome.