Humbio Ch 18: Cellular Reproduction

Front 1

Mitosis

Back 1

The division mechanism that divides the nucleus of a somatic cell.
-Body grows and replaces/repairs skin cells through mitosis

Front 2

Meiosis

Back 2

The duplication of chromosomes and division of cytoplasm in germ cells within the gonads, in order to halve the diploid chromosome number (2n->n) and create 4 haploid daughter cells.

Front 3

Chromosome

Back 3

A long DNA particle combined with proteins (together, also known as chromatin).

Front 4

Diploid Cell

Back 4

A cell having two of each type of chromosome (shorthand of 2n indicates that a cell is diploid, "n" standing for the number of chromosomes in a full set.

Front 5

Autosomes

Back 5

Pairs 1-22 of the chromosomes carrying hereditary trait instructions.

Front 6

Sex Chromosomes

Back 6

Pair of 23 in the chromosome chain that determines a person's biological sex.

Front 7

Chromatin

Back 7

DNA combined with a protein.

Front 8

Reductional Division

Back 8

A process that halves the diploid number of chromosomes (2n) to a haploid gamete (n) that ends up with one partner from each pair of homologous parent chromosomes.

Front 9

SIster Chromatids

Back 9

Chromosome and its copy that stay together for most of the division process.

Front 10

Centromere

Back 10

A "pinched" region in that provides docking sites for microtubules that move chromosomes when a cell nucleus divides.

Front 11

Spindle

Back 11

2 sets of microtubules extending from the two "poles" of a chromosome

Front 12

Centrioles

Back 12

"Poles" on a cell's cytoskeleton. A microtubule set overlaps another at the equator between these two poles.

Front 13

Preparation for Cell Division

Back 13

1. Duplicate chromosomes
2. Duplicates coil over one another
3. Chromosome condense (Division begin)
4. Coils sorted into parcels for Daughter Cells
5. Centromeres develop on sister chromatids, attach to spindle and move into new positions

Front 14

Cell Cycle

Back 14

1. Interphase: Cell growth - prepare to divide
2. Mitosis: Cytoplasm divide - daughter cells enter interphase

Front 15

Rule of Cell Reproduction

Back 15

Cell must receive a copy of the parent cell's DNA, otherwise the cell won't develop or function properly.

Front 16

Interphase

Back 16

1. G1- Cell grows
2. S- Cell's DNA copied, chromosomes duplicated
3. G2- Prepare for division
4. M- Mitosis: chromosomes (duplicated DNA) sorted into 2 sets, cytoplasm divides

Front 17

Mitosis

Back 17

Interphase, Prophase, Metaphase, Anaphase, Telophase, Interphase 2, etc.

Front 18

Prophase

Back 18

The DNA and its proteins condense as new microtubules move centrioles to opposite ends of the cell. Nuclear envelope begins to disintegrate.

Front 19

Metaphase

Back 19

Microtubules penetrate nuclear region, form bipolar spindles, which attach to sister chromatids and condense to line up in equator.

Front 20

Anaphase

Back 20

Attachments between sister chromatids break, creating two separate chromosomes. They are moved to opposite spindle poles by microtubules.

Front 21

Telophase

Back 21

Two clusters of chromosomes decondense, patches of new membrane fuse to form a new nuclear envelope. Mitosis complete.

Front 22

Interphase 2

Back 22

After Telophase 1, there are 2 daughter cells, both diploid, each nucleus having two of each type of chromosome.

Front 23

Cytokinesis

Back 23

During anaphase, after sister chromatids have separated, the cytoplasm divides.

Front 24

Cleavage Furrow

Back 24

Plasma membrane sinks inward at former spindle equator pinching until forming two cells.

Front 25

Meiosis

Back 25

Division of germ cells, halving number of chromosomes in daughter cells.
Divides 2x = 4 haploid cells
(Prophase I => Telophase II, no Interphase between I & II)

Front 26

Spermatogenesis

Back 26

Formation of gametes in male (sperm).
Large diploid germ undergoes meiosis, divides into 4 spermatids, grow tails, turn into sperm.

Front 27

Oogenesis

Back 27

Formation of gametes in female (egg).
One oocyte ovulated, second oocyte receives most of cytoplasm. Both cells enter meiosis II, but only pass if secondary oocyte is fertilized. Result is 1 large ovum cell & 3 small polar bodies.

Front 28

Crossover Sites

Back 28

Nonsister chromatids break at same places along their length and put new combinations together.

Front 29

Genetic Recombination

Back 29

Exchange of chromosome pieces. Leads to variation in details of inherited traits, as a gene may have several chemical forms.

Front 30

How does meiosis produce new combinations of genes in gametes?

Back 30

Move maternal and paternal chromosomes into gametes at random, creating new combinations of chromosomes in sperm and eggs.

Front 31

Segregation

Back 31

Separation of gamete pairs.

Front 32

Pleitropy

Back 32

A single gene having wide-ranging effects on the expression of traits on a chromosome.

Front 33

Sickle-Cell Enemia

Back 33

Inherited by receiving two copies of the recessive Hb^S (homozygous for recessive allele).

Front 34

Codominance

Back 34

2 contrasting traits are both expressed.

Front 35

Multiple Allele System

Back 35

A gene that has 3+ alleles.

Front 36

Penetrance

Back 36

The probability that someone who inherits an allele will have the phenotype associated with it.

Front 37

Polygenic Traits

Back 37

Result from combined expression of several genes (skin & eye color)