Pestle Bio Notes - Cell Biology & Molecular Biology (MCQS)

Vocabulary flashcards covering key terms and definitions from the lecture notes.

Prophase (mitosis)

Stage where chromosomes condense and spindle begins to form. In meiosis I, prophase involves synapsis of homologous chromosomes and crossing over at chiasmata.

Prophase I (Meiosis)

Stage in meiosis where homologous chromosomes pair (synapsis) and crossing over occurs at chiasmata, increasing genetic variation.

Synapsis

Pairing of homologous chromosomes during prophase I of meiosis.

Crossing over

Exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I.

Chiasmata

Points where crossing over occurs between homologous chromosomes.

Metaphase I

Homologous chromosome pairs line up along the metaphase plate in meiosis I.

Metaphase II

Sister chromatids align at the metaphase plate during meiosis II.

Active transport

Movement of ions or molecules against their concentration gradient, requiring energy (usually ATP) and membrane proteins.

Concentration gradient

Difference in the concentration of a substance across a space or membrane.

ATP

Adenosine triphosphate; the cellular energy currency.

Transmembrane proteins

Proteins that span the lipid bilayer; include pumps and channels used in transport.

Cell/plasma membrane

The phospholipid bilayer that encloses the cell and regulates entry/exit of substances.

Cyclins

Regulatory proteins that control progression through the cell cycle by activating CDKs.

CDKs

Cyclin-dependent kinases; enzymes activated by cyclins to drive cell cycle events.

M-cyclin

Cyclin that promotes mitotic spindle assembly; concentration peaks at M phase.

G1 cyclin

Cyclin that helps prepare the cell for DNA synthesis (G1/S transition).

S cyclin

Cyclin that triggers DNA replication during S phase.

Nucleus

Membrane-bound organelle containing the cell’s genetic material (DNA) in eukaryotes.

Mitochondria

Organelle producing ATP; contains its own circular DNA supporting endosymbiotic theory.

Chloroplasts

Organelle responsible for photosynthesis in plants and some algae; contains its own DNA.

Golgi apparatus

Organelle that modifies, packages, and ships proteins; vesicles destined for the cell membrane originate here.

Vesicles

Small membrane-bound sacs that transport materials within the cell and to the membrane for secretion.

Rough endoplasmic reticulum

ER with ribosomes; site of synthesis of proteins destined for secretion or membranes.

Lysosome

Organelle containing enzymes that digest macromolecules.

Nucleoid

Region in prokaryotes where naked DNA is located; not membrane-bound.

Prokaryote

Unicellular organism lacking membrane-bound organelles; DNA is circular and in the nucleoid.

Eukaryote

Organism with membrane-bound organelles and a defined nucleus.

Cell wall (plant)

Rigid cellulose layer outside the plasma membrane providing support and protection.

Plasmodesmata

Cytoplasmic channels through plant cell walls enabling intercellular communication.

Ribosomes (70S vs 80S)

Ribosomes in prokaryotes are 70S; those in eukaryotes are 80S; sites of protein synthesis.

Free ribosomes

Ribosomes in the cytoplasm that synthesize cytoplasmic proteins.

Glycoproteins

Proteins with carbohydrate chains attached; involved in cell recognition and signaling.

Glycolipids

Carbohydrate-containing lipids in the cell membrane involved in cell recognition.

Cholesterol (membrane)

regulates membrane fluidity and stability.

Phospholipid bilayer

Two-layer arrangement of phospholipids forming the cell membrane; hydrophilic heads face outside, hydrophobic tails inside.

Integral proteins

Membrane proteins that span the bilayer and function in transport or signaling.

Peripheral proteins

Membrane proteins attached to the surface; roles in signaling, adhesion, and enzymes.

Glycoproteins/Glycolipids

Membrane components for cell recognition and signaling.

Passive transport

Movement of substances down their concentration gradient without energy input.

Simple diffusion

Passive movement of small nonpolar molecules directly through the membrane along a gradient.

Facilitated diffusion

Passive transport of polar/charged substances via membrane channels or carriers.

Osmosis

Diffusion of water across a semi-permeable membrane down its water potential gradient.

Active transport (membrane)

Movement of substances against their gradient, requiring ATP (e.g., Na+/K+ pump).

Vesicle transport/exocytosis

Vesicles bud from the Golgi, move along cytoskeleton, fuse with membrane and release contents.

Emergent properties

New properties that arise when components operate as a system, not visible in individual parts.

SA:V ratio

Surface area-to-volume ratio; higher ratios enhance exchange but increase heat loss.

Interphase

Cell cycle phase comprising G1, S, and G2, where growth, DNA replication, and preparation occur.

G1 phase

Cell growth and normal metabolic functions; organelles replicate.

S phase

DNA replication; each chromosome is copied to form sister chromatids.

G2 phase

Preparation for mitosis; further growth and organelle duplication; DNA checked for errors.

Mitosis

Nuclear division: prophase, metaphase, anaphase, telophase; results in two diploid daughter cells.

Cytokinesis

Cytoplasm divides, forming two separate identical cells.

Meiosis

Cell division producing four haploid gametes with genetic variation; includes crossing over.

Oogenesis

Meiotic production of eggs; unequal cytokinesis yields one large ovum and polar bodies.

Autosomes vs sex chromosomes

Autosomes are non-sex chromosomes; sex chromosomes determine sex (X and Y in humans).

X-linked recessive

Traits carried on the X chromosome; often more in males; females can be carriers.

Karyotyping

Visualization of chromosomes to detect structural abnormalities or aneuploidy.

Punnett grid/diagrams

Tool to predict genotype and phenotype ratios in genetic crosses.

Monohybrid cross

Cross examining the inheritance of a single trait.

Dihybrid cross

Cross examining the inheritance of two traits simultaneously.

Genetic disorders (Down syndrome)

Down syndrome: trisomy 21 due to nondisjunction during meiosis.

DNA replication (enzymes)

Helicase unwinds DNA; DNA polymerase builds new strands; semi-conservative replication.

Genetic code

Codons (RNA) specify amino acids; genetic information is translated into proteins.

Complementary base pairing

A pairs with T (or U in RNA); G pairs with C.

DNA ligase

Enzyme that seals nicks in the sugar-phosphate backbone during replication.

Transcription vs Translation

Transcription converts DNA to mRNA; translation uses mRNA to synthesize a polypeptide.

Enzymes

Proteins that catalyze biochemical reactions by lowering activation energy.

Active site

Region of an enzyme where substrates bind to form an enzyme-substrate complex.

Competitive inhibition

Inhibitor competes with substrate for the active site, reducing enzyme activity.

Non-competitive inhibition

Inhibitor binds away from the active site, altering enzyme shape and reducing activity.

Denaturation

Loss of protein structure and function due to heat, pH change, or chemicals.

Glycogen

Polysaccharide in animals for glucose storage.

Amylose/Amylopectin

Polysaccharides of starch; amylose is mostly 1,4 linkages; amylopectin contains 1,6 branches.

Cellulose

Polysaccharide with β-1,4 linkages; provides structural support in plants.

Sugars: glucose, galactose, fructose

Monosaccharides; glucose is a primary energy source; galactose and fructose are components of disaccharides.

Disaccharides (lactose, maltose, sucrose)

Carbohydrates formed from two monosaccharides; maltose (glucose+glucose), lactose (glucose+galactose), sucrose (glucose+fructose).

Polysaccharides (starch, glycogen, cellulose)

Long chains of sugars used for energy storage (starch, glycogen) or structure (cellulose).

Proteins & amino acids

Polymers of amino acids; primary structure determines folding and function.

Hemoglobin

Conjugated protein in blood that transports O2.

Bt crops

Genetically engineered crops producing pest-resistant proteins.

Hershey-Chase experiment

Experiment supporting DNA as genetic material using labeled viruses and bacteria.

Photosynthesis (photophosphorylation and photolysis)

Light-dependent reactions split water (releasing O2) and generate ATP via photophosphorylation; Calvin cycle fixes CO2 using ATP and NADPH.

Chemiosmosis

Proton gradient across a membrane drives ATP synthesis via ATP synthase.

Respiration vs fermentation (yeast)

Glycolysis followed by aerobic respiration or fermentation; fermentation regenerates NAD+ for glycolysis.

Osmosis example (root uptake)

Water moves from higher to lower potential across a membrane, e.g., root cells absorb water from soil.

Endosymbiotic theory

Mitochondria and chloroplasts originated as free-living prokaryotes; evidenced by 70S ribosomes, circular DNA, double membranes.

Pasteur’s Swan-neck Flask

Experiment disproving spontaneous generation by showing sterile broth remained sterile unless exposed to air microbes.

Plasma membrane vs cell wall

Plasma membrane controls transport; cell wall provides structural support in plants.

Oogenesis

Formation of eggs in females; unequal cytokinesis produces one large ovum and polar bodies.