32 terms

Chapter 6: Meiosis, Sexual Reproduction & Embryo Development.

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sexual reproduction
Reproduction that requires 2 parents and produces offspring that are genetically different from the parents, each other and other members of their species.
genetic diversity
Inherited genetic differences in a species or variation.
diploid number (2n)
A body cell that has 2 sets of chromosomes or a full set of chromosomes. In humans the diploid number is 46.
haploid number (n)
A gamete that has one set of chromosomes or half the number. In humans the haploid number is 23.
gametes
Specialized cells for reproduction such as egg and sperm.
fertilization
When two gametes, such as egg and sperm, fuse (join) to form a zygote.
zygote
A diploid cell created when two haploid gametes fuse together. A zygote receives half of its chromosomes from its male parent and half from its female parent.
embryo
When the zygote has undergone mitosis and cell division to develop into an embryo.
meiosis
A process of cell division that results in gametes with half the number of chromosomes or one set of chromosomes. This is where the nucleus divides twice - meiosis I and meiosis II.
homologous chromosomes
A pair of matching chromosomes: one chromosome from each parent that are the same size, shape, banding pattern and have the same genes.
crossing over
Occurs in meiosis (prophase I) where parts of homologous chromosomes exchange segments of DNA.
independent assortment
Occurs in meiosis (anaphase I) where homologous chromosomes separate at the equator and move toward opposite poles of the cell.
karyotype
A picture of the homologous chromosomes arranged in order and identified by their size and banding pattern.
mating
Process where gametes arrive in the same place at the same time.
external fertilization
When a sperm and egg cell unite outside of the body of the parents.
internal fertilization
When a sperm and egg cell unite inside the body of the parent - the female.
pollination
Transfer of the male part to the female part of the plant. Form of internal fertilization that occurs in plants.
pollen
Structure that transfers the male gamete during pollination. Transported by wind or a pollinator (bee, bat, moth)
ovules
Female plant structure that contains the egg.
pollen tube
A passage way for the sperm to get to the egg.
embryonic development
The early development of an organism. In humans - the first 2 months after fertilization.
morula
A ball of cells created by mitosis after fertilization occurs.
blastula
Second stage of development after the morula where a hollow ball of cells is created.
gastrula
Stage of development after the blastula where the embryo is organized into 3 layers: ectoderm, mesoderm and endoderm.
ectoderm
Outside tissue layer of gastrula that will form skin and nervous system
mesoderm
Middle tissue layer of gastrula that will form kidneys, muscles, blood vessels, reproductive organs and bones.
endoderm
Inner tissue layer of gastrula that will form lungs, liver and the lining of the digestive system.
assisted reproductive technologies
Methods used to help correct infertility in couples through medical treatment.
artificial insemination (AI)
A reproductive technology where sperm is collected from a male and injected into a female so fertilization can occur.
in vitro fertilization (IVF)
A reproductive technology where sperm and egg are combined in a petri dish and fertilization takes place in the dish. 2 or 4 days after fertilization, the embryo(s) transferred to the female's uterus.
gamete intrafallopian transfer (GIFT)
A reproductive technology where an egg cell is removed from a woman's ovaries and combined with sperm cells to create a mixture. This mixture is then injected into the woman's fallopian tubes so fertilization can occur in the woman's body.
intracytoplasmic sperm injection (ICSI)
A reproductive technology where a single sperm cell is injected into an egg cell. The resulting zygote is then inserted into the uterus of the woman.