PPT 1 - MIDTERMS DEV BIO

Fertilization

The essential first step in the creation of a new organism through sexual reproduction.

Sperm

A tiny messenger carrying half of the genetic blueprint.

Egg

A larger cell holding the other half of the blueprint.

Zygote

The very first cell of a new life, formed by the fusion of sperm and egg.

Fertilization Importance

Restores the correct number of chromosomes, creates genetic diversity, and kicks off embryonic development.

Sperm Preparation (Capacitation)

Sperm undergo changes in the female reproductive tract, making them capable of fertilization.

Acrosome Reaction

The sperm releases enzymes, allowing it to penetrate the egg's outer layers.

Prevention of Polyspermy

The egg changes its surface to prevent other sperm from entering.

Fusion of Genetic Material

The sperm and egg's genetic material combine, forming the zygote.

Activation

The zygote begins dividing and developing into an embryo.

Gametogenesis

The formation of gametes (sperm and egg).

Meiosis

A special type of cell division involved in gametogenesis.

Spermatogenesis

Sperm formation, occurs in the testes.

Oogenesis

Egg formation, occurs in the ovaries.

Haploid

Having one copy of each chromosome (sperm and egg).

Diploid

Having two copies of each chromosome (zygote).

Sperm Capacitation Location

Female reproductive tract (uterus and fallopian tubes).

Hypermotility

Increased swimming activity of capacitated sperm.

Cholesterol Removal

A change during capacitation that makes the sperm membrane more fluid.

Increased Calcium Permeability

A change during capacitation that triggers hypermotility and the acrosome reaction.

Corona Radiata

Outermost layer of the egg, made up of cells that surround the egg.

Zona Pellucida

Thick, glycoprotein layer beneath the corona radiata.

Egg Plasma Membrane

The actual outer boundary of the egg cell.

Sperm Transport

The journey of sperm from deposition to the egg.

Cervical Mucus

Acts as a filter for sperm, changes consistency during the menstrual cycle.

Uterine Contractions

Assist in moving sperm towards the fallopian tubes.

Fallopian Tubes

Where fertilization typically occurs.

Chemotaxis

The egg may release chemical signals that attract sperm.

Thermotaxis

There may be slight temperature differences that guide sperm.

Egg Activation

The series of events in the egg after fertilization, kickstarting development.

Calcium Surge

A dramatic increase in intracellular calcium levels, a hallmark of egg activation.

Cortical Reaction

Release of cortical granules, reinforcing the block to polyspermy.

Pronuclei

The male and female nuclei after sperm entry into the egg.

Cleavage

The first cell division of the zygote, marking the start of embryogenesis.

Sperm Penetration

Meeting the egg, penetrating the corona radiata, binding to the zona pellucida, acrosome reaction, and fusion with the egg plasma membrane.

Fast Block to Polyspermy

Rapid change in egg membrane potential to prevent other sperm from fusing.

Slow Block to Polyspermy

Cortical reaction that modifies the zona pellucida to prevent further sperm binding.

DNA Replication (in fertilization)

Occurs in each pronucleus before fusion.

Pronuclear Fusion

The male and female pronuclei fuse, forming the zygote nucleus.