Chapter 9

gastrocoel

--cavity in the gastrula formed by cells moving into the blastocoel --becomes the digestive tract

blastocoel

--cavity inside blastula

blastula

--hollow sphere covered with cells --produced from morula

pachytene

--synapsis is complete and chromosomes appear doubled and are referred to as tetrads

gastrula

-2 layered structure that is produced from the blastula by process called gastrulation

leptotene

-chromatin coils and becomes traceable structures

morula

-cluster of cells produced from zygote --64 or more cells

zygotene

-homologous chromosomes synapse or pair

monad

-refers to half of a dyad --refers to chromosome in Anaphase II

tetrad

-refers to the doubled homologo us chromosomes in pachytene

diploid

2n body cells and zygotes (fertilized eggs)

Diploid

A cell that contains 2 haploid sets of chromosomes.

Karyotype

A micrograph of the arrangment of chromosomes visible in a cell during metaphase.

Mitosis

A process of cell division that forms two new nuclei, each has the same number of chromosomes.

Polar Bodies

A short lived product of the formation of gametes by meiosis.

Autosome

Any chromosome that is not a sex chromosome.

Asexual vs Sexual Reproduction

Asexual: No joining of reproductive cells; produces offspring from 1 parent Sexual: Production of offspring from 2 parents, Joins reproductive cells

Homologous Chromosome

Chromosomes that have the same sequence of genes, have the same structure, and pair during meiosis.

Cytokinesis

During mytosis, the nucleus of a cell divides. Cytokenisis is the division of the cell's cytoplasm.

Binary fision

Is the division of a prokaryote cell into 2 offspring cells

involves two divisions with only one duplication of DNA

Meiosis

occurs in reproductive tissue only

Meiosis

Meiosis Facts

Meiosis -Sex cells -Starts with one -Sex cells used for sexual reproduction -Cells begin diploid -The homologous chromosomes are split apart from each other in Anaphase I, and the sister chromatids split apart form each other in Anaphase II -Phases same as Mitosis except doubled -Produces 4 haploid daughter cells

Mitosis Facts

Mitosis -Normal cells -Normally functioning cells -Begin as diploid -Goes through Prophase, Metaphase, Anaphase, Telophase -Produces 2 duaghter cells -Daughter cells still diploid

Ootid

One mature egg cell.

Chromosome

One of the structures in the nucleus that is amde up of DNA and protein.

Chromatid

One of two strands of a chromosome

Oogenesis

Oogenesis a diploid reproductive cell divides meiotically to produce one mature egg cell.

Spermatogenesis

Production of sperm cells.

Gametes

Reproductive cells, have only half the number of chromosomes as body cells. haploid reproductive cells.

Sex chromosomes

Sex chromosomes are chromosomes that determine the sex of an organsim and they may also carry genes for other characteristics.

Meiosis

The process of cell division during which the number of chromosomes decreases to half the original number by 2 divisions of the nucleus which results in the production of sex cells.

Asexual Reproduction

Types: Binary fission Cloning Spore formation Budding

Two types of gametes

a. isogametes -structurally alike, functionally different b. heterogametes -structurally different, functionally different --2 types: sperm (male gamete) egg (female gamete)

gamete

are haploid (n) and the zygote and body cells are diploid (2n)

Centromere

area where the chromatids of a chromosome are attached

homologous

chromosomes that are identical in form, location of the centromere, and in the arrangement of the genes

Haploid

contain only one set of chromosomes, half the number of chromosomes than in diploid cells

zygote

fertilized egg

haploid

n or gametes

blastopore

opening form the gastrocoel to the outside of the gastrula

synapsis

process in which homologous chromosomes pair during zygotene

Advantage(genetic variation)

provides for differences within a species

dyad

refers to half of a tetrad --refers to chromosomes in Anaphase I

Gastrulation

results in the formation of 3 embryonic or germ layers: ectoderm--outer layer endoderm--inner layer mesoderm--middle layer

Function of meiosis

to produce gametes with the haploid number of chromosomes

oogenesis

•Meiosis in the female •End product 1 egg and 2 or 3 polar bodie

spermatocyte

•Meiosis in the male •End product--4 sperm cells