mcat biology

Nucleoid Region

DNA region in prokaryotes

Nucleolus

Makes ribosomes

Peroxisomes

are small, membrane-bound organelles found in eukaryotic cells. They contain enzymes that are involved in a variety of metabolic reactions, including the breakdown of fatty acids and the detoxification of harmful substances such as hydrogen peroxide.

Rough ER

Accept mRNA to make proteins.

Smooth ER

Detox and make lipids

Golgi Apparatus

Modify/ dsitribute proteins. Only in eukaryotes

Vesicular Transport

COPII → forward (function of the golgi)

Cisternal Maturation (function of the golgi)

Vesicles travel in retrograde, New Cis made, cis/medial/trans/exit

Centrioles

9 groups of microtubules, pull chromosomes apart

lysosomes

Lysosomes are membrane-bound organelles found in animal cells that contain digestive enzymes capable of breaking down various biomolecules, including proteins, nucleic acids, carbohydrates, and lipids. They play a crucial role in cellular waste disposal, recycling of cellular components, and defense against invading microorganisms.

Plasmids

In prokaryotes. Carry DNA not necessary for survival.

Microfilaments

Actin

Microtubules

Tubulin

Intermediate filaments

keratin= vimentin; desmin=lamin

bacilli

rod

cocci

sphere

spirilla

spiral

obilgate aerobe

requires o2

obligate anaerobe

dies in o2

facultative anaerobe

toggle between aerobic/anaerobic

areotolerant anarobe

Does not use oxygen gas but tolerates it

gram postive

\-is purple

* thick peptidoglycan/lipoteichoic acid cell wall

gram -

* pink-red
* thin peptidoglycan cell wall and outer membrane

\

What is a eukaryote

* Etc in mitochonrdira
* large ribomsomes
* reproudces via mitosis

What are prokaryotes

* ETC in cell membrane
* small ribosomes
* reproduce via binary fission
* plasmids carry dna material
* may have virulence factors.
* plasmids that integrate into genome are episomes

Prions

decrease solubility.

infectious proteins. Trigger misfolding. alpha-helical → beta-pleated sheets

viroids

plant pathogens

Epithellia

parenchyma (functional parts of organ)

simple: one layer

stratified: multiple layers

pseudostratified: one layer (looks multi, but is just 1)

cuboidal: cube shape

columnar: long and marrow

squamous: flat, scale-like

connective

stroma (support, extracellular Matrix ). Bone, cartiliage, tendon, blood

transformation

gets genetic info from environment

Conjugation

transfer of genetic information via conjugation bridge. (Hfr → recipient)

Transduction

transfer using bacteriophage

transposons

genetic info that can insert/remove themselves

capsid

protein coat

envelope

some have lipid envelope

virion

individual virus particles

bacteriophage

bacteria virus. Tail sheath injects DNA/RNA

viral genome

May be DNA or RNA. Single or double stranded

if single strand: postive sense

can be translated by host cell

if single strand: negative sense

RNA replicase must synthesize a complimentary strand, which can then be translated

retrovirus

single stranded. Reverse transcriptase needed to make DNA

Bacteriophage lytic

virions made until cell lyses

life cycles lysogenic

virus integrates into genome as pro virus or prophage. Goes dormant until stress activates it

Cell Cycle G1

Make mRNA and proteins to prep for mitosis

G0

A cell will enter G0 if it does not need to divide

g1 checkpoint

Cell decides if it should divide. P53 in charge

S

DNA replicated

G2

Cell growth. Make organelles

G2 checkpoint

check cell size & organelles

M

Mitosis and cytokinesis

Positive growth signals

1) CDK + cyclin create a complex 2) Phosphorylate Rb to Rb + P

3) Rb changes shape, releases E2F

4) Cell division continues

Negative growth signals

1. CDK inhibitors block phosphorylaylation of Rb
2. So, E2F stays attached


1. cell cycle halts

x-linked disorders

males express, females can be carriers

y-chromosome

little genetic info. SRY gene = “Sorry you’re a male”

Semen

Sperm + seminal fluid

Bulbourethral Glands

Make viscous fluid to clean out urethra

Seminal Vesicles & Prostate Gland

Make alkaline fluid to help sperm survive acidic environment of female reproductive tract

Seminiferous tubules

Site of spermatogenesis. Nourished by sertoli cells.

Epididymis

Stores sperm. sperm gain motility.

Vans Deferens

Raise/ lower testes

Ejaculatory duct:

The ejaculatory ducts are short tubes that connect the vas deferens to the urethra in male reproductive anatomy. They are responsible for transporting semen from the seminal vesicles and the vas deferens to the urethra during ejaculation.

Urethra

The urethra is a tube-like structure that carries urine from the bladder to the outside of the body during urination. In males, it also serves as a passage for semen during ejaculation.

Penis

the name of male gentile

Mitosis

ploidy of 2n throughout

Prophrase

DNA condenses. Centrioles migrate to opposite poles and microtubules form. Nuclear envelope disappears.

Metaphrase

“Meet in the middle”. Chromosomes meet in middle.

Anaphase

“Apart”. Sister chromatids separate and move to opposite poles.

Telophrase

Chromosomes decondense. Nuclear membrane forms. Cytokinesis occurs.

Nondisjunction

When sister chromatids don’t separate properly during anaphase. Result in aneuploidy.

Prophase 1

Chromosomes condense, nuclear membrane dissolves, homologous chromosomes form bivalents, crossing over occurs.

Metaphrase 1

Spindle fibers from opposing centrosomes connect to bivalents (at centromeres) and align them along the middle of the cell.

Anaphase 1

Homologous pairs move to opposite poles of the cell. This is disjuction and it accounts for the law of segregation.

Telophrase 1

Chromosomes decondense, nuclear membrane MAY reform, cell divides (cytokinesis), forms two halpoid daughter cells of unequal sizes.

Prophrase 2

Chromosomes condense, nuclear membrane dissolves, centrosomes move to opposite poles (perpendicular to before)

Metaphrase 2

Spindle fibers from opposing centrosomes attach to chromosomes (at centromere) and align them along the cell equator.

Anaphrase 2

Spindle fibers contract and separate the sister chromatids, chromatids (now called chromosomes) move to opposite poles.

Telophase 2:

Chromosomes decondense, nuclear membrane reforms, cell divide (cytokinesis) to form four haploid daughter cells.

Ovaries

have follicles that produce ova. Controlled by FSH and LH

Oogenesis

Production of female gametes

Estrogen

Response to FSH. Develops rep tract, thickens uterine wall.

Progesterone

Response to LH. Maintains/protects endometrium. “Estrogen establishes; progesterone protects the endometrium”

Pathway

Egg → peritoneal sac → fallopian tube/oviduct

FSH (Follicle Stimulating hormone)

males: triggers spermatogensis, stumulates sertoli cells.

females: stimulates development of ovarian follicles.

LH (Luteinizing hormone)

Males: Causes interstitial cells to make testosterone.

Females: Induces ovulation.

Fertilization

Occurs in the ampulla of fallopian tube.

Sperm’s acrosomal enzymes penetrate corona radiate & zona pellucia.

Acrosomal enzymes inject pronucleus.

Cortical reaction releases ca2+ which depolarizes ovum membrane and makes it impenetrable.

Morula

Early. Solid mass of cells

\

Blastula

implants in endometrial lining

fluid filled blastocoel

trophoblast → chorion/placenta

inner cell mass → organism

Gastrulation

Archenteron leads to blastopore

Ectoderm (outside)

Nervous system = skin, hair, nails, mouth, anus.

Mesoderm

Muscoskeleton = circulatory system, gonads, adrenal cortex.

Endoderm

Endocrine glands = GI tract, respiratory tract, bronchi, bladder, stomach.

inside stuff

Neurulation

Mesoderm develops a notochord. Notochrod induces Ectoderm.

\
Ectoderm → Neural folds to neural crest cells to peripheral nervous system→ Neural tube to central nervous system

Totipotent

Stem cell. Can be any type of cell

Pluripotent

Can be any cell except those found in placental structures. STEM cells.

Multipotent

More specialized. Can be multiple types of cells. STEM cells.

Adult STEM cells

Multipotent and require treatment w/ transcription factors.

Fetal Hemoglobin (HbF)

Increased of oxygen affinity than adult hemoglobin

How are oxygen and carbon dioxide exchanged?

diffusion

Fraternal twins

dizygotic

Identical twins

monozygotic