MCAT BIOLOGY

Proximal Convoluted Tubule

Where does 75% of sodium get reabsorbed?

Ascending Loop of Henle

Where does 25% of salts get reabsorbed?

Distal Convoluted Tubule

Where does a small amount of sodium get absorbed

Renin

Enzyme that is increased during low salt levels in the body. Detected by baroreceptors. Leads to a increase in aldosterone

Aldosterone

Hormone released from adrenal cortex. Increases reabsorption of sodium in the collecting duct and water (passively)

ADH/Vasopressin

Hormone produced by the hypothalamus. Released due to low water levels in the body. Increases reabsorption of water in the collecting duct.

Where are steroid hormones stored in the cell

Nowhere

Where are protein hormones stored in the cell?

Granules

Flow of blood through the heart

Apoptosis of the webbing in-between digits

What process prevents Syndactyly

What is a brush border enzyme

enzyme that is present in the luminal surface of cells lining the duodenum. Includes disaccharidases (maltase/isomaltase/lactase/sucrase) and peptidases (dipeptidase/enteropeptidase)

What is a epigenome and what does it do

Chemicals that surround the DNA and can change the gene expression without changing the DNA itself

Describe the menstural cycle as a whole (ovarian/hromones’’/endometrium)

Ectopic pregnancy

When a fertilized egg implants in the wrong area AKA not in the endometrium (usually the fallopian tubes)

Myosin is ____, and actin is _____

Myosin is thick, and actin is thin

Parts of a sarcomere

Z line- end of sarcomere

M line- middle of sarcomere

I band- thIn filaments only

H band- only tHick filaments

A band- All of the thick filament, including the overlapped portions with thin filaments

Describe the path of gluconeogenesis

Describe the path of glycolysis

Describe the path of CAC

What is the rate determining step of CAC

The conversion of isocitrate to alpha-ketoglutarate

3 NADH and 1 FADH2

How much NADH and FADH2 is produced from 1 cycle of CAC

How much ATP is made from 1 NADH

2.5 ATP

How much ATP is made from 1 FADH2

1.5

How much ATP is produced from 1 cycle of CAC

7.5 from NADH + 1.5 from FADH2 + 1 from GTP= 10 ATP TOTAL

Thymus is a immune organ that matures and creates T cells

What is the function of the thymus

What is the function of T cells

Destroys an infected cells that contain foreign antigens

Where are B cells produced and what do they do

Be cells are matured and created in bone marrow and are involved in antibody production

contain large fragments of DNA and include both coding (exon) and non coding (introns) regions of genome

Genomic library

cDNA library

constructed by reverse transcription and lacks the non coding regions (introns)

What are the three steps of PCR

Denaturation- heat up DNA to unwind double helix

Annealing- lower temperatures slightly so primers can bind

Elongation- DNA polymerase uses primers to add the new complementary strand

Why can’t human polymerase be used in the PCR process

The high temperatures needed in denaturation will also denature human polymerase. Taq comes from a extremophile so its polymerase will be able to remain intact during denaturation

When carbohydrates are not available, what energy resources are used instead

Fats and proteins but fats are prioritized over proteins

What is hydrostatic pressure

pressure of liquids pushing against each other

What is oncotic pressure

Pressure that develops due to differences in osmotic gradients due to solutes

What are the three parts of a bacterial growth curve

Lag phase, log phase and death phase

In conjugation how is DNA transferred

Genetic material is transferred from F⁺ to F^- unidirectionally (only F^- gets new genetic info)

Variable expressivity

people with the same genotype that have different phenotype

the proportion of people with a certain genotype that express the phenotype is usually less than those who have the gene

Reduced penetrance

when a heterozygote expresses a phenotype that is a mix of two homozygous genotypes

Incomplete dominance

Codominance

when more than one dominant allele exists for a given gene

What are the subunits of eukaryotic ribosomes

60S and 40S (80S)

What are the subunits of prokaryotic ribosomes

50S and 30S (70S)

Where does a repressor bind

at the operator

Positive inducible

No transcription occurs until a inducer binds

Positive repressible

Transcription occurs until a inhibitor binds

Negative inducible

Repressor is normally bound but a inducer deactivates it

Negative repressible

Transcription occurs until a repressor binds

Describe movement of water and solutes in the loop of Henle

Descending limb- water exits

Ascending limb- solute exits

What alleles do people of different blood types pass

AB passes A and B

A passes A

B passes B

O passes O

What is nondisjunction

When chromosomes do not properly separate in meiosis. Can result in trisomy or monosomy

Germline vs somatic cells

Germline cells can be used to make gametes while somatic cells do not

What comes from the ectoderm

Skin, eyes, nervous system

What comes from the mesoderm

Skeletal system, notochord, excretory system, circulatory system, reproductive system

What comes from the endoderm

Lining of digestive tract, repsiratory system excretory system, productive system and liver, prancreas, thymus, thyroid gland, parathyroid gland

What is a energy source used in translation

GTP