oat bio unit 24

this is the one where i gave birth remember?

oocyte

immature egg inside ovary

ovum

mature egg outside of ovary

• Corona radiata: superficial layer

• Zona pellucida: protective glycoprotein layer

• Perivitelline space: between zona pellucida and plasma membrane; prevents polyspermy.

sperm

• Head: contains acrosome to dissolve egg and also a 1n nucleus.

• Midpiece: filled with mitochondria.

• Tail: propellor

capacitation

a process to mature sperm when they enter the uterus and fallopian tubes, caused by acidic vaginal wall and basic seminal fluid.

• A glycoprotein coat is added to each sperm in epididymus.

• Enzymes in the uterus digest glycoprotein coat.

• Also destabilizes the acrosome and induces tail hyperactivity.

fertilization

Haploid sperm fuses with haploid ovum to make a diploid zygote.

• Only ~300 sperm make it to the egg.

• The zona pellucida has 4 binding sites.

• ZP3 makes sperm release acrosin, which breaks down the ZP, allowing a sperm inside.

• The sperm equator fuses with the membrane, and releases nucleus into egg.

sex determination

• Eggs only carry and X chromosome

• Sperm can carry X or Y

• This means a 50/50 chance of a boy or girl.

• XX = girl, XY = boy

polyspermy

One egg fertilized by multiple sperm.

• Fast block: egg immediately emits sodium ions upon being fertilized to depolarize the cell, preventing other sperm from fusing.

• Slow block: calcium ions are sent towards the egg membrane for the cortical reaction, which flood the perivitelline space.

cleavage (yes please)

rapid cell division with no cell growth (1 parent to 2 daughter cells). A cleavage furrow divides the cells.

blastomeres

resulting cells formed by cleavage of a fertilized ovum.

holoblastic cleavage

cleavage EQUALLY divides fertilized ovum in two pieces.

meroblastic cleavage

partial or unequal cleavage, leading to different sized blastomeres.

determination

cell decides which type of cell it will be in the future, and chooses which genes to express.

differentiation

Cell is expressing desired genes for whichever role it will fulfill (happens after determination)

indeterminant blastomeres

haven’t picked a role yet. They can separate from the rest of the zygote and form a new organism

radial cleavage

spiral cleavage

protosomes

determinant and undergo spiral cleavage.

deuterosomes

indeterminant and undergo radial cleavage.

blastulation

Zygote → morula → blastula

gastrulation

blastula becomes gastrula

• Gives rise to germ layers (ectoderm, mesoderm, ectoderm)

trophoblast

gives rise to the placenta (chorion) and is responsible for implantation into the endometrium of the uterus.

• Also produces human chorionic gonadotropin (HCG) which stops menstruation

inner cell mass

bilaminar disc made of epiblast and hyperblast. The epiblast has a cavity with amniotic fluid.

frog eggs

• Very large in size, and are deposited in water.

• Vegetal pole: slow rate of cleavage, lots of yolk

• Animal pole: fast rate of cleavage, little yolk

• Grey crescent is created by overlapping of poles.

bird eggs

• Have a blastodisc instead of a blastula (tiny white circle on yolk).

• Chalaza: white strings that anchor yolk to the rest of the egg.

• Elongated blastopore.

amniotes

Birds, reptiles, mammals

anamniotes

Amphibians and fish

chorion

responsible for gas, nutrient, and waste exchange.

allantois

stores and later exchanges embryo waste products like uric acid, and later becomes the umbilical cord.

yolk sac

gives nutrients to the embryo.

amnion

membrane surrounding embryo with amniotic fluid.

induction

Cell influences the development of neighboring cells.

neurulation

• Notochord thickens a structure called the neural plate, which later folds.

• The folds pinch off to later become the brain and spinal cord.

ectoderm derivatives

• Epidermis: hair, nails, sweat glands, mammary glands.

• Neural tube (nervous system)

• Adrenal medulla

• Skull: bones, muscles, connective tissues

• PNS: sensory neurons and glial cells

endoderm derivatives

• Epithelial lining: GI, respiratory, and urinary tract

• Excretory system

• Liver, lungs, pancreas

• Thyroid and thymus

mesoderm derivatives

• Bones, cartilage, joints, muscles

• Connective tissue

• Circulatory system

• Lymphatic system, kidneys, spleen

poop cleavage