12.4

What do Mendel’s principles require?

* that an organism with two parents must inherit a single copy of every gene from each parent
* when than organism produces gametes, those two sets of genes must be separated so that each gamete contains just one set of genes.

Budding

A type of asexual reproduction where a whole other organism is grown on the back of the parent.

Regeneration

A type of asexual reproduction where an organism is cut in half and then forms two organisms.

Genome

all the genetic information you inherit from your parents

Homologous

each of the chromosomes from the male parent has a corresponding chromosome from the female parent. **Based on size and location of the centromere.**

Homologous explained

Humans have 46 chromosomes total

\-23 from the male parent

\-23 from the female parent

Each of the 23 chromosomes from the male parent has a corresponding chromosome from the female parent meaning they are homologous.

Chromosome

Long, condensed strands of DNA that carry genes in specific segments of specific chromosomes

Diploid

A cell with two complete sets of homologous chromosomes and genes. 2n

Haploid

A cell with one complete set of chromosomes and genes. n

Meiosis

a process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Has two parts: meiosis I and meiosis II (miotic divisions). Turns one diploid cell into four haploid cells.

Meiosis I

(the separation of homologous chromosomes)

Genetic recombination

two daughter cells are different from each other and from the parents.

Interphase I

the chromosomes replicate to form sister chromatids connected at the centromere.

Prophase I

**Synapsis**- each replicated chromosome pairs with its corresponding homologous chromosome to form a tetrad containing 4 chromatids.

When the chromatids pair they can (but not always) **cross over**- bits and pieces of the homologous chromosomes are exchanged to __produce new combinations of alleles on each chromosome__. **Chiasmata** is the location where it occurs. This creates __genetic variation__.

At the end, a spindle will attach to each tetrad.

Metaphase I

paired homologous chromosomes line up in the center of the cell.



**Independent assortment-** the way that each pair of homologous chromosomes line up is independent from one another. This creates

Anaphase I

spindle fibers shorten to pull each homologous chromosome pair toward oppisite ends of the cell. This is also called **segragation**.

Telophase I

a nuclear membrane forms around each cluster of chromosomes.

At the end, each cell has %%half the amount of chromosomes but double the amount of genetic information%% so we need to get rid of the sister chromatids.

Cytokinesis I

two new haploid cells are formed however, the daughter cells do not have complete sets of chromosomes, sort of like they were suffled like a deck of cards and not evenly distributed.

Meiosis II

*A second meiotic division to separate sister chromatids to turn 2 haploid cells into 4.* NO REPLICATION BEFORE HAND

Interphase II

pause to make materials needed for division, NO DNA REPLICATION

Prophase II

each chromosome containing two chromatids become visable.

Metaphase II; Anaphase II, Telophase II, and Cytokinesis

the chromosomes align in the center and spindle fibers connect to their centromere; the chromatids are pulled to opposite sides of the cell; a nuclear envelope forms around the chromomes; the cell splits to form two daughter cells (since this happens twice, there are a total of 4).

What happen to the 4 haploid cells?

Develop into gametes for sexual reproduction

Female-egg

Male- sperm

Meiosis vs Mitosis

Meiosis


1. early step in sexual reproduction.
2. Homologous chromosomes are separated and each daughter cell only receives a haploid set. (the sorting and rearranging creates genetic variation)
3. 2n →n
4. Four genetically different haploid cells

\
Mitosis


1. a form of asexual reproduction
2. Each daughter cell receives a complete diploid set of chromosomes
3. 2n→2n
4. Produces 2 genetically identical diploid cells

Linkage group

groups of genes that are almost always inherited together on a chromosome. Assort between other linkage groups from there independently from there.

Principles Morgan used to create gene maps

The farther apart two genes were on a chromosome- the more frequently they are crossed over which decreases the frequencey which they are linked



The closer they are- crossing should be rare increasing the frequencey which they are linked.

Gametogenesis

the process of making gametes (sperm and egg).

Spermatogenesis

creation of sperm from a spermatogonial stem cell.




1. Primary spermatocyle- 2n



**miosis I**




2. Secondary spermatocyle- 2 cells with n each.



**miosis II**




3. Early spermatid- 4 cells with n each.



**differentation**




4. For every spermatagonium there are 4 viable sperm!

Oogenesis

creation of a mature egg cell (ovam).




1. Primary oocyte- 2n



***cytoplasm divides unevenly***




2. First polar body (small); Secondary oocyte (large)



***miosis***




3. two polar bodies; one polar body and mature ovum

Facts about reproduction

* Mature ovum has to be as big as possible to create a target for the sperm.
* Sperm can survive inside of someone for up to 7 days.
* The two nuclei of the sperm and egg to form a zygote.

Order of processes of development

Miosis→ fertilization →mitosis→differentation