Biology Review for MCAT

Flashcards covering key concepts in biology relevant to the MCAT exam.

Sensory vs Motor Neurons

Sensory neurons are afferent, carrying signals to the CNS; motor neurons are efferent, carrying signals away from the CNS.

Nucleoid

The DNA region in prokaryotes where most of their DNA can be found; prokaryotes do not have a nucleus.

Nucleolus

A dense region within the nucleus of eukaryotes responsible for ribosome production, not membrane-bound.

Ribosomes

Molecular machines responsible for protein synthesis, found in both prokaryotes and eukaryotes.

Prokaryotes vs Eukaryotes

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have these structures.

Peroxisomes

Organelles that break down fatty acids and detoxify harmful substances.

Endoplasmic Reticulum (ER)

Rough ER synthesizes proteins; Smooth ER is involved in lipid synthesis and detoxification.

Golgi Apparatus

The organelle responsible for modifying, sorting, and packaging proteins and lipids for secretion.

Centrioles

Cylindrical structures involved in cell division, forming spindle fibers that separate chromosomes.

Lysosomes

Cellular organelles that contain enzymes for digestion and recycling cellular waste.

Plasmids

Circular DNA molecules in prokaryotes that can replicate independently of chromosomal DNA.

Gram Staining

A technique to classify bacteria as purple (Gram+) or pink (Gram-) based on cell wall characteristics.

Obligate Anaerobes

Organisms that cannot survive in the presence of oxygen, requiring an anaerobic environment.

Facultative Anaerobes

Organisms that can survive with or without oxygen, employing aerobic or anaerobic processes.

Aerotolerant Anaerobes

Organisms that do not use oxygen for growth but can tolerate its presence.

Nucleotide vs Chromosomal Mutations

Nucleotide mutations affect the sequence of nucleotides; chromosomal mutations affect larger segments of DNA.

Mitosis

The process of cell division that results in two identical daughter cells with diploid chromosome numbers.

Meiosis

The process that results in gametes with half the chromosome number (haploid) for sexual reproduction.

Dominant vs Recessive Alleles

Dominant alleles are expressed with one copy; recessive alleles require two copies to show expression.

Penetrance

The proportion of individuals with a specific genotype that express the associated phenotype.

Antibodies

Protein molecules produced by B cells that target specific antigens.

Skeletal Muscle

Striated, voluntary muscle responsible for body movement and contraction, under somatic control.

Smooth Muscle

Involuntary muscle found in organs, under autonomic control, responsible for movement within the body.

Cardiac Muscle

Striated, involuntary muscle tissue of the heart, capable of myogenic activity.

Renal Portal System

The blood flow pathway through the kidneys, involving arteries, afferent arterioles, glomeruli, and efferent arterioles.

Bicarbonate Buffer System

A system that helps maintain pH in the body; essential for regulating acidity and basicity in blood.

Complement System

A part of the innate immune system that helps opsonize pathogens and induce lysis of bacteria.

Neurotransmitters

Chemical signals used for communication between neurons at synapses.

Hardy-Weinberg Principle

A principle stating that allele and genotype frequencies in a population remain constant in the absence of evolutionary influences.

Recombination Frequency

The likelihood that two alleles will be separated during crossing over in meiosis.

Mendel's Law of Segregation

The two alleles for a trait segregate during gamete formation.

Epidermis

The outermost layer of skin that provides a barrier to the external environment.

Endocrine System

A system of glands that release hormones into the bloodstream to regulate various body functions.