MCAT Bio/biochem

Cell Cycle: Interphase G1

Cell growth: contents duplicate
Restriction point G0

Cell cycle: Interphase S

DNA replication; produces two sisters

Cell cycle: Interphase G2

Double checks for errors
Restriction point G0

Cell cycle: Prophase

Chromosomes condense, spindle forms, nuclear envelope breaks down (2n)

Cell cycle: Metaphase

Chromosomes align at the center (2n)

Cell cycle: Anaphase

Sister chromatids pull apart (4n)

Cell cycle: Telophase

Chromosomes migrate towards ends of poles; nuclear envelope reforms (4n)

Cell cycle: Cytokineses

Cell pinches, cytoplasm divides (2n)

Meiosis

Produces 4 NON-indentical gametes (4× 1n); each embryo cell receives a complete set of genes with half the genetic material.

Meiosis ploidy

2n → Interphase → 2n → Meiosis I → 2× 1n → Meiosis II → 4× 1n

Species

Group of organisms that can produce fertile offspring

Population

Group of the SAME species in the SAME area

Community

Groups of DIFFERENT species in the SAME area

Irreversible/regulatory steps of Glycolysis enzymes

Hexokinase, phosphofructokinase (PFK1), pyruvate kinase

Embryogenesis

FBIGN: Fertilization, blastulation, implatation, gastrulation, neurolation

Embryogenesis: Fertilization

Acrosomal enzymes: hydrolytic, allows sperm to reach egg

Embryogenesis: Blastulation

Morula forms → blastula

Embryogenesis: Implantation

Blastula to endometrium, trophoblast → yolk sac → placenta

Embryogenesis: Gastrulation

Development of three layers: Ectoderm, mesoderm, endoderm

Ectoderm

Outermost layer → skin, nervous system

Mesoderm

Musculoskeletal, circulatory, notochord

Endoderm

Epithelial linings

Embryogenesis: Neurolation

Ectoderm → nervous system development
Ectoderm → neural folds → neural tube → CNS

_____ + _____ = H2CO3 = H+ + HCO3-

CO2 + H2O

Shift right on bicarb-buffer system

Response to a rise in pH

H+ increases, pH decreases (increases acidity)
Bicarb increases

Shift left on bicarb-buffer system

Response to drop in pH

H+ decreases, pH increases (decreases acidity)

CO2 increases

Bacteria reproduce via

binary fission

____ surge is responsible for triggering ovulation

LH

Transcription location

Nucleus

Translation location

Cytoplasm (ribosomes)

Chance mutations _________ survivability and make descendent cells antibiotic resistant.

Increase

Conjugation

Genetic material is transferred from a donor bacterium to a recipient bacterium through conjugation bridge (sex pilus)

Transformation

Gets genetic information from the environment (ex. dead cells)

Transduction

Uses viral DNA (bacteriophage) to infect, multiply, then incorporate DNA into infected cell.

Endosymbiotic theory

mitochondria are descendents of prokaryotes that were engulfed by endocytosis into a vesicle lined with a membrane, derived from the cell membrane of a eukaryotic host.

Inner mitochondrial membrane = plasma membrane of a prokaryote

Extracellular Ca++ concentration is (</>) than intracellular Ca++ concentration

> : there is more Ca++ OUTSIDE the cell than inside

Obligate parasite

Constrained to one function

Oogenesis: before birth

Mitosis (2n → 2× 2n → 4× 2n), begins meiosis, stops at P1

Oogenesis: between birth and puberty

Nothing happens (OO)

Oogenesis: after puberty

Meiosis continues until menopause

Oogenesis: ploidy and names

Oogonia (2n), primary oocyte (2n), secondary oocyte (n), ovum (n)

Spermatogenesis: before birth

Mitosis (2n → 2n)

Spermatogenesis: birth to puberty

Nothing happens (S)

Spermatogenesis: after puberty

Mitosis continues, meiosis I and meiosis II and differentiation

Spermatogenesis: ploidy and names

Spermatogonia (2n), primary spermatocyte (2n), secondary spermatocyte (2× 1n), spermatid (4× 1n), spermatozoa (x4 × 1n)

FSH function in menstruation

Growth and maturation of follicles

Estrogen function in menstruation

Increases thickness of endometrium; peaks at ovulation

Progesterone function in menstruation

Peaks AFTER menstruation, prepares uterus for potential implantation

Calcitonin

Produced by parafollicular cells; decreases Ca++ resorption to decrease blood Ca++

Parathyroid hormone

Produced by parathyroid glands; Increases Ca++ bone resorption to increase blood Ca++

Posterior pituitary hormones

ADH/vasopressin + oxytocin

ADH

Acts at nephron collecting ducts to increase H2O reabsorption to increase BP through regulation of aquaporins.

Oxytocin

Love hormone, acts on brain, uterus, and breasts.

Adrenal medulla hormones

EPI/NE

Adrenal cortex hormones

Mineralcorticoids (aldosterone), glucocorticoids (cortisol), androgens (DHEA, androstenedione)

Mineralcorticoids

Aldosterone

Glucocorticoids

Cortisol

Androgens

DHEA, androstenedione

Pancreatic B cells

Insulin to lower BG

Pancreatic a cells

Glucagon to increase BG

GI hormones

Secretin, gastrin, CCK

Kidney hormones

Erythropoietin (increases RBC production)

Heart hormone

ANP (inhibits aldosterone in kidneys)

Thymus hormones

Thymosin: T-cell development

Pineal gland

Melatonin: circadian rhythm

Secretin

Decreases HCl, increases HCO3- (bicarb) = shift left, decrease in H+ to neutralize acidic chyme.

Secreted by S cells in the duodenum

Gastrin

Secreted by G-cells of stomach; aids in HCl secretion

CCK

Small intestine; increases bile release, increase in satiety

Enteropeptidase

Small intestine, activates trypsinogen

Gut bacteria produce which vitamin

Vitamin K + B7 (biotin)

Pancreas hormones in digestion

Lipase, amylase, trypsin, chymotrypsin, carboxypeptidase

Pancreatic lipase

Lipid hydrolysis

• Converts fats → FFA + glycerol

Pancreatic amylase

Hydrolyzes starch

• Converts polysaccharides → disaccharides

Carboxypeptidase function

Removes C-terminal of AA

Chymotrypsin

Protein and polypeptide digestion

Where is bile produced?

Liver

Where is bile stored?

Gallbladder

Bile micelles function in digestion

Emulsifies large fat particles into droplets

Digestion is governed by the ______ nervous system

Enteric

Respiratory acidosis

Association: HIGH CO2

Cause: COPD, asthma (decrease in ventilation)

Compensation: kidneys: excrete H+, reabsorb HCO3-

Respiratory alkalosis

Association: low CO2

Cause: high altitudes (increase in ventilation)

Compensation: Kidneys: decrease in H+ excretion, increase in HCO3- excretion to decrease pH

Metabolic acidosis

Association: low HCO3-

Cause: Kidney failure (decrease in HCO3- reabsorption), exercise (increase in lactic acid), diarrhea (loss on HCO3-)

Compensation: respiratory- increase in ventilation to decrease CO2 and H+

Metabolic alkalosis

Association: HIGH HCO3-

Cause: antacids (increase HCO3-), vomiting (decrease in H+ from stomach)

Compensation: respiratory: decrease in ventilation to increase CO2 and H+

Layers of epidermis

Come, Let’s Get SunBurned

Corneum, lucidum, granulosum, spinosum (langerhan cells), basale

Layers of the dermis

Papillary: loose connective tissue

Reticular: sweat glands, blood vessels, hair follicles

Hypodermis: connective tissue, fat, fibrous tissues

Langerhan cells: immune system

Specialized macrophages of the stratum spinosum; presents T-cells to activate the immune system

Creatine phosphate energy system

Creatine + ATP ←→ Creatine phosphate + ADP

Creatine phosphate

Stores ATP

During contraction, which elements of the sarcomere remain constant?

A lines

During contraction, which elements of the sarcomere decrease?

H and I bands

Calcium binds to _____ during skeletal muscle excitation contraction coupling

Troponin

______ shifts to expose myosin-binding sites

Tropomyosin

When ATP is hydrolyzed in the cross-bridge, what happens?

ATP → ADP + Pi; recocks myosin head to revert back to a HIGH energy state.

Latent period in excitation contraction coupling

Depolarization of AP’s down to T-tubules and sarcolemma; AP is just spreading without visible tetanus.

Nucleotide level mutations

Point (silent, missense, nonsense), and frameshift

Chromosomal level mutations

Deletion/insertion, duplication, inversion, translocation

Genetic drift

Change in composition of a population

Founder effect

Example of genetic drift; small group of individuals from a larger population establishes a new, isolated population.

Reduced genetic diversity

Bottlenecked

Hardy-Weinberg equilibrium

P² + 2PQ + Q² = 1

P + Q = 1

P: dominant allele frequency

Q: recessive allele frequency

Dihybrid cross: heterozygous + heterozygous

9 dominant/dominant

3 recessive/dominant

1 recessive/recessive