MCAT Biomolecules, Enzymes & Cell Biology - Fill-in-the-Blank Flashcards

Fill-in-the-blank flashcards covering biomolecules, enzyme kinetics, cell structure, transport, the cell cycle, mitosis, and meiosis for MCAT review.

__ is the level of protein structure characterized by a linear sequence of amino acids joined by peptide bonds.

Primary structure

An α-helix is a form of protein __ structure stabilized by intrachain hydrogen bonds.

secondary

β-Pleated sheets consist of parallel or antiparallel strands held together by __ hydrogen bonds.

interchain

Hydrophobic interactions, ionic bonds, disulfide bridges, and hydrogen bonds all stabilize a protein’s __ structure.

tertiary

Hemoglobin is an example of a protein with __ structure composed of four subunits.

quaternary

Peptide bonds are formed by a __ synthesis (condensation) reaction.

dehydration

The molecular formula C₆H₁₂O₆ represents a __.

monosaccharide (e.g., glucose)

Sucrose is a disaccharide composed of __ + fructose.

glucose

Lactose is a disaccharide composed of glucose + __.

galactose

Maltose is a disaccharide composed of glucose + __.

glucose

Glycogen stores energy in animals and contains α-1,4 and α-1,6 __.

glycosidic bonds

Cellulose contains __ β-1,4 glycosidic bonds that humans cannot digest.

linear

The plant structural polysaccharide that is indigestible to humans is __.

cellulose

The main energy-storage polysaccharide in plants is __.

starch

The main energy-storage polysaccharide in animals is __.

glycogen

A triglyceride is composed of one glycerol molecule esterified to __ fatty acids.

three

Phospholipids are described as __ because they possess both hydrophobic and hydrophilic regions.

amphipathic

Steroids share a core structure of __ fused rings.

four

Cholesterol is classified as a __ type of lipid.

steroid

Saturated fatty acids are typically __ at room temperature.

solid

Unsaturated fatty acids are typically __ at room temperature.

liquid

DNA contains the sugar __.

deoxyribose

RNA contains the sugar __.

ribose

In DNA, adenine pairs with __ via two hydrogen bonds.

thymine

In RNA, adenine pairs with __.

uracil

Guanine pairs with __ by three hydrogen bonds in both DNA and RNA.

cytosine

A nucleotide consists of a phosphate group, a five-carbon sugar, and a __ base.

nitrogenous

Enzymes lower the __ energy of a reaction without changing ΔG or ΔH.

activation

Km is the substrate concentration at __ of Vmax.

one-half (½)

Competitive inhibition increases __ while leaving Vmax unchanged.

Km

Noncompetitive inhibition leaves Km the same but decreases __.

Vmax

Uncompetitive inhibition decreases both Km and __.

Vmax

Metal ion helpers such as Mg²⁺ are called __.

cofactors

Organic helpers like NAD⁺, FAD, or CoA are called __.

coenzymes

The __ fit model describes the flexible enzyme–substrate interaction.

induced

A reaction with ΔG < 0 is __ (spontaneous/exergonic).

spontaneous

Hydrolysis of ATP releases approximately __ kJ mol⁻¹ of free energy.

−30.5

Prokaryotic ribosomes are __S in size.

70

Eukaryotic ribosomes are __S in size.

80

Prokaryotic genomic DNA is typically __ rather than linear.

circular

Plant cell walls are primarily composed of __.

cellulose

Prokaryotes divide asexually by __ fission.

binary

The __ is the organelle where aerobic respiration generates ATP.

mitochondrion

The rough endoplasmic reticulum is studded with ribosomes and synthesizes __ proteins.

secreted/membrane

The smooth ER functions in lipid synthesis and cellular __.

detoxification

The __ apparatus modifies, packages, and traffics proteins.

Golgi

__ contain hydrolytic enzymes responsible for intracellular digestion and autophagy.

Lysosomes

Peroxisomes degrade fatty acids and detoxify H₂O₂ using the enzyme __.

catalase

Free ribosomes synthesize proteins that remain in the __.

cytosol

Bound ribosomes synthesize proteins destined for secretion or __ insertion.

membrane

The passive movement of water across a semipermeable membrane is called __.

osmosis

The Na⁺/K⁺ pump is an example of __ transport.

active

Phagocytosis and pinocytosis are forms of bulk transport known collectively as __.

endocytosis

Actin-based filaments of the cytoskeleton are called __.

microfilaments

Microtubules are polymers of the protein __.

tubulin

__ filaments provide mechanical strength and structural support.

Intermediate

DNA replication occurs during the __ phase of the eukaryotic cell cycle.

S

The spindle-assembly checkpoint occurs during __ of mitosis.

metaphase (M phase)

Cleavage furrow formation during cell division occurs in __.

cytokinesis

Genetic crossing over occurs during __ of meiosis.

prophase I

Homologous chromosomes separate during __ of meiosis.

anaphase I

Sister chromatids separate during __ of meiosis and during mitotic anaphase.

anaphase II

Mitosis produces __ genetically identical diploid daughter cells.

two

Meiosis ultimately produces __ genetically unique haploid gametes.

four

Crossing over does __ occur during mitosis.

not