Cellular Energy, Photosynthesis, and Molecular Genetics Review

Vocabulary practice flashcards generated from lecture worksheet notes covering thermodynamics, enzymes, cell transport, photosynthesis, and genetics.

ATP

An energy molecule consisting of the nitrogenous base adenine, the sugar ribose, and 3 phosphate groups.

Activation Energy ($E_a$)

The energy barrier required to initiate a chemical reaction; enzymes speed up reactions by lowering this curve.

Active Site

The specific region on an enzyme where substrate molecules bind.

Enzymatic Reaction Mechanism

The process where a substrate binds to an enzyme's active site, undergoes a reaction to form products, and is released while the enzyme remains intact.

Coenzymes

Non-protein organic helpers (like $\text{NADP}^+$) that assist enzymes in carrying out chemical reactions.

Induced Fit Model

The active model of enzyme binding in which the shape of the enzyme's active site shifts when the substrate enters to form a tighter fit.

Feedback Inhibition

A cellular control mechanism where an end product acts as an inhibitor by binding to an allosteric site on the first enzyme ($E_1$) of a pathway to prevent wasteful overproduction.

Passive Transport

Movement across a membrane (such as osmosis) that occurs down the concentration gradient without the use of chemical energy.

Active Transport

Membrane movement processes that require ATP energy, including the sodium-potassium pump, endocytosis, and exocytosis.

Facilitated Diffusion

A transport process across membranes down a concentration gradient that does NOT require ATP energy.

Grana

Stacks of thylakoid membranes located inside a chloroplast.

Stroma

The fluid-filled interior region surrounding the thylakoids inside a chloroplast.

Thylakoids

Pigment-embedded membranes in chloroplasts where solar energy is captured during photosynthesis.

Photosynthesis Redox Statement

In photosynthesis, $H_2O$ is oxidized into $O_2$, and $CO_2$ is reduced into a carbohydrate ($CH_2O$).

Light-Dependent Reactions vs. Calvin Cycle

Light reactions occur in the thylakoid membrane to convert light, $H_2O$, $\text{NADP}^+$, ADP, and $P_i$ into $O_2$, ATP, and NADPH. The Calvin cycle occurs in the stroma using $CO_2$, ATP, and NADPH to yield G3P, ADP, and $\text{NADP}^+$.

Calvin Cycle Math

It takes 3 turns of the Calvin cycle to produce 1 net G3P molecule, and 6 turns to build 1 complete 6-carbon glucose molecule.

NADPH

Acts as a reducing agent that donates electrons to hydrogen ions during the Calvin cycle.

ATP in Calvin Cycle

Provides chemical energy to phosphate groups during the Calvin cycle reactions.

Bundle-Sheath Cells

Specialized cells around leaf veins in $C_4$ plants where the Calvin cycle is isolated to prevent oxygen interference.

Chargaff's Rules

The rule that DNA base ratios match complementary pairs; for example, if a DNA molecule contains $22\%$ Cytosine (C), it contains $22\%$ Guanine (G), $28\%$ Adenine (A), and $28\%$ Thymine (T).

DNA Ladder Backbone

The structural sides of the DNA double helix made up of alternating deoxyribose sugars and phosphate groups.

Hydrogen Bonds

Chemical bonds that hold nitrogenous base pairs together across the middle of the DNA double helix.

Semiconservative Replication

The mechanism of DNA replication resulting in double helices that each contain one original parent strand and one newly synthesized strand.

DNA Helicase

The enzyme responsible for breaking hydrogen bonds to unzip double-stranded DNA during replication.

Central Dogma

The core pathway of genetic information transfer in cells: $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$.

mRNA Processing in Eukaryotes

Nuclear modifications made to pre-mRNA including addition of a $5'$ cap, addition of a poly-A-tail, and splicing (removal of non-coding introns and joining of coding exons).

Anticodon

The nucleoside sequence on tRNA used to bind to the complementary 3-nucleotide codon on mRNA during translation.

Aminoacyl-tRNA

The tRNA complex that enters the A site of a ribosome during translation elongation.

The three sequential phases of translation:

1) initiation, 2) elongation, and 3) termination.

Barr Body

An inactivated, highly condensed X chromosome in female mammalian cell nuclei formed by chromatin condensation into heterochromatin.

Calvin cycle

The Calvin cycle occurs in the stroma using $CO_2$, ATP, and NADPH to yield G3P, ADP, and $\text{NADP}^+$.