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