Ultimate OAT Biology Section

Gonads

Reproductive structures responsible for producing gametes.

Ovary

Produces eggs (ova). Females have two ovaries.

Testis

Site of sperm and male sex hormone production enclosed within the scrotum for temperature regulation.

Somatic cell

Diploid, non-reproductive cells (E.g., muscle cells, skin cells, nerve cells).

Germ cell

Diploid cells of embryonic origin and gives rise to gametes via meiosis (E.g., spermatogonium, oogonium).

Gamete

Haploid sex cells (E.g., egg and sperm).

Viviparity

Birth to live young that receive nutrients directly from the mother's body.

Oviparity

Fertilized eggs get laid then hatch later.

Ovoviviparity

Internally fertilized eggs hatch and give birth to live young who continue to receive nutrients from the yolk of the egg.

Oviduct (Fallopian/Uterine Tube)

Responsible for moving the eggs from the ovary to the uterus; site of fertilization (where the sperm meets the egg).

Sertoli cells

Stimulated by FSH and surround and nurture the sperm.

Fimbriae

Sweep the egg into the fallopian tube once released from the ovary.

Interstitial cells (Leydig cells)

Secrete male hormones (E.g., testosterone and androgens) in the presence of LH.

Cervix

The muscular canal that connects the vagina to the uterus.

Uterus

Muscular chamber in which the embryo develops until birth; zygote attaches to uterine wall after fertilization.

Vagina

Muscular canal that serves as a birth canal during delivery; connected to the uterus via the cervix.

Epididymis

Coiled tube attached to each testicle that serves as the site of final sperm maturation and storage.

Vas deferens

Transfers sperm from each epididymis to the urethra.

Seminal vesicles

Excrete fluid into the vas deferens upon ejaculation.

Penis

Transports semen into vagina.

Acrosome

Lysosome-like organelle that penetrates the egg.

Pro-nucleus

Haploid (23 chromosomes).

Mid-piece

Plethora of mitochondria for energy.

Tail

Flagellum that produces motion.

Blastocyst

Stage of early embryonic development that follows the morula stage.

Morula

A solid ball of cells resulting from the division of a fertilized ovum.

Zygote

Fertilized egg.

Implantation of blastocyst

The process where the blastocyst attaches to the uterine wall.

Week 5

Heart begins beating.

Week 8

Development of embryo has reached fetus stage.

Week 40

Development has reached full term.

Oogenesis

The process of egg formation in females.

Spermatogenesis

The process of sperm formation in males.

Primary oocytes

Oogonia that have begun meiosis but stopped in prophase I.

Primordial follicle

Structure formed when primary oocytes are surrounded by a single layer of granulosa cells.

Primary follicles

Follicles that develop from primordial follicles when granulosa cells enlarge and increase in number.

Secondary follicles

Follicles that form when fluid-filled vesicles develop and theca cells arise on the outside.

Mature follicles

Follicles that form when vesicles create a single antrum.

Follicular phase

The phase of the menstrual cycle involving the development of the egg and secretion of estrogen.

Ovulation

The midcycle release of the egg, triggered by a surge of LH.

Luteal phase

The phase following ovulation characterized by secretion of estrogen and progesterone from the corpus luteum.

Secondary oocyte

An oocyte that is released from the ovary and completes meiosis II only if fertilized.

Corpus luteum

The structure formed from the remaining follicle after ovulation that secretes hormones.

Corpus albicans

The scar formed when the corpus luteum degenerates if the egg is not fertilized.

Human chorionic gonadotropin (hCG)

Hormone secreted by the placenta that maintains the corpus luteum during pregnancy.

Negative feedback loop

A regulatory mechanism where increased hormone levels suppress further hormone release.

GnRH

Gonadotropin-releasing hormone released by the hypothalamus to stimulate FSH and LH release.

FSH

Follicle-stimulating hormone that promotes the development of sperm and follicles.

LH

Luteinizing hormone that triggers ovulation and testosterone release.

Leydig cells

Cells in the testes that produce testosterone in response to LH.

Sertoli cells

Cells in the testes that support and promote the development of sperm.

Estrogen

Hormone produced by follicles that regulates the menstrual cycle.

Progesterone

Hormone produced by the corpus luteum that prepares the endometrium for implantation.

Menstrual Cycle

The monthly cycle of changes in the female reproductive system, including the follicular, ovulation, and luteal phases.

Fertilization

The process by which a sperm cell unites with an oocyte to form a zygote.

Epididymis

The structure where sperm are stored after maturation in the testes.

Testes

Male reproductive organs where spermatogenesis occurs.

Fallopian tube

The tube through which the egg travels from the ovary and where fertilization occurs.

Granulosa cells

Cells that surround oocytes and are involved in follicle development.

Atoms

Single unit made up of neutrons, protons, and electrons

Ionic Bonds

Transfer of e- from one atom to another atom of very different electronegativity

Hydrolysis

Uses water to break polymers into monomers

Dehydration Reaction

Links monomers to form polymers, forming H2O in the process

Covalent Bonds

Sharing of e- between atoms of similar electronegativities

Molecule

Groups of 2+ atoms held together by chemical bonds due to electron interactions

Nonpolar

Equal e- sharing

Polar

Unequal e- sharing, forms dipole

Macromolecules

Large molecules (polymers) formed from the bonding of smaller molecules (monomers)

Hydrogen Bonds

Weak bond between a hydrogen atom and an electronegative atom (F, O, or N)

Monomer (Amino acid)

Building block of proteins

Monomer (Monosaccharide)

Building block of carbohydrates

Monomer (Nucleotide)

Building block of nucleic acids

Polymer (Peptide)

Chain of amino acids linked by peptide bonds

Polymer (Polysaccharide)

Chain of monosaccharides linked by glycosidic bonds

Polymer (Nucleic acid)

Chain of nucleotides linked by phosphodiester bonds

Polymer (Hydrocarbon chain)

Chain of hydrocarbons linked by covalent carbon-carbon bonds

Function of Lipids

Store energy

Function of Nucleic Acids

Encode, express, and store genetic info

Function of Proteins

Structure, transport, defense, storage, enzymes

Function of Lipids

Insulation, energy storage, endocrine signaling, cell structure

Triglycerides

Glycerol + 3 fatty acids

Phospholipids

2 fatty acids + phosphate group attached to glycerol backbone

Steroids

Three 6-membered rings + one 5-membered ring

DNA Structure

Bases are A, T, C, G. Contains deoxyribose sugar and 2 complementary antiparallel (5' to 3') strands of double helix.

RNA Structure

Has bases A, U, C, and G, with a ribose sugar and is single stranded.

Chargaff's Rule

A & T, and G & C are always present in equal amounts (i.e., if DNA is 20% A, it is also 20% T).

Chemical Reactions and Energy

Determined by concentration of reactants and products

Anabolic

Small molecules assemble to form a larger molecule

Catabolic

Large molecules are broken into smaller molecules

Exergonic

Free energy is released (spontaneous with −Δ𝐺)

Endergonic

Free energy is absorbed (nonspontaneous with +Δ𝐺)

Kinetic Energy

Energy in motion (i.e., jumping)

Potential Energy

Stored energy (i.e., glycogen)

ATP Hydrolysis

An exergonic reaction that facilitates endergonic reactions

Enzyme Function

Enzymes act as catalysts by lowering the activation energy needed for a reaction

Active Site

The area of the enzyme where the substrate binds

Allosteric Site

A secondary location where an effector binds (effectors can be activators or inhibitors)

Induced Fit Model

When the substrate binds the enzyme, it forms the enzyme-substrate complex

Vmax

The maximum velocity of the reaction at peak substrate saturation

Michaelis Constant (Km)

The substrate concentration at which the rate of the reaction is half of the maximum velocity