Cell Biology, Metabolism, and Genetics Flashcards

A complete set of vocabulary flashcards derived from the lecture notes covering cellular transport, enzymes, photosynthesis, respiration, DNA replication, and mitosis.

Phospholipid bilayer

Two layers of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward, forming the main structure of the cell membrane.

Fluid mosaic model

Model describing the cell membrane because its components, such as proteins and cholesterol, can move laterally within the phospholipid bilayer.

Semi-permeable

Property of a membrane that allows some substances to pass through while blocking others, controlling movement in and out of the cell.

Diffusion

The passive movement of particles from a region of high concentration to a region of low concentration down a concentration gradient without requiring ATP.

Osmosis

The passive movement of water molecules across a semi-permeable membrane from a region of low solute concentration to high solute concentration without ATP.

Hypotonic solution

A solution with a lower solute concentration than the cell, causing water to enter an animal cell by osmosis until it swells and may lyse.

Hypertonic solution

A solution with a higher solute concentration than the cell, causing water to leave the cell by osmosis and make an animal cell shrink or crenellate.

Turgid

The firm state of a plant cell when water enters by osmosis in a hypotonic solution, causing the vacuole to swell against the cell wall.

Plasmolysis

The shrinking of a plant cell's vacuole and pulling away of its membrane from the cell wall when placed in a hypertonic solution.

Active transport

The movement of substances from low to high concentration against a gradient, requiring carrier proteins and ATP energy.

Facilitated diffusion

The passive movement of polar or large molecules down a concentration gradient through protein channels or carriers without ATP.

Endocytosis

A form of bulk transport where the cell membrane folds inward to engulf large particles or liquids, forming a vesicle using ATP.

Exocytosis

A form of bulk transport where a vesicle fuses with the cell membrane to release its contents outside the cell using ATP.

Surface area to volume ratio (SA:V)

A ratio that decreases as a cell grows, slowing diffusion relative to cell volume and driving cells to divide.

Enzymes

Biological catalysts made of protein that speed up chemical reactions by lowering the activation energy without being consumed or changed.

Lock and key model

Enzyme model where a specific substrate fits precisely into a rigid, complementary active site on the enzyme.

Induced fit model

Model where the enzyme active site changes shape slightly upon substrate approach to fit tightly around it and strain its bonds.

Denaturation

Irreversible structural breakdown of an enzyme's active site due to high temperature or extreme pH, preventing substrate binding.

Competitive inhibitor

A molecule with a similar shape to the substrate that binds directly to the active site, blocking the substrate from binding.

Non-competitive inhibitor

A molecule that binds to an allosteric site on an enzyme, altering the active site's shape so the substrate cannot bind.

Photosynthesis chemical equation

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$$

Thylakoids/grana

Stacked membranes inside chloroplasts that absorb light energy and host the light-dependent phase of photosynthesis.

Stroma

The fluid portion of the chloroplast surrounding grana where the light-independent phase (Calvin cycle) occurs.

Photolysis

The light-driven reaction in thylakoid membranes that splits water molecules into oxygen gas and hydrogen ions.

Chlorophyll

Green pigment in thylakoid membranes that absorbs red and blue light energy while reflecting green light to excite electrons.

Limiting factor

An environmental factor in shortest supply that directly controls and restricts the maximum rate of a biological process.

Aerobic respiration chemical equation

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$$

ATP (Adenosine triphosphate)

The universal energy currency of the cell that releases energy when broken down into ADP + Pi and is recharged during respiration.

Cristae

Folded inner membranes of mitochondria that provide a large surface area for the electron transport chain.

Matrix

The internal fluid of the mitochondrion containing enzymes necessary for carrying out the Krebs cycle.

Glycolysis

The initial stage of respiration in the cytoplasm where glucose is split into pyruvate, yielding a small amount of ATP.

Krebs cycle

The second stage of aerobic respiration taking place in the mitochondrial matrix, breaking down pyruvate to release $CO_2$, ATP, and hydrogen.

Electron transport chain

The final stage of aerobic respiration on mitochondrial cristae where hydrogen combines with oxygen to form water, generating a high yield of ATP.

Lactic acid fermentation

Anaerobic pathway in animal cells converting glucose into lactic acid and small amounts of ATP, leading to muscle cramp and fatigue.

Alcoholic fermentation

Anaerobic pathway in plant and yeast cells converting glucose into ethanol, carbon dioxide, and small amounts of ATP.

Oxygen debt

The additional oxygen required following anaerobic exercise to transport and break down accumulated lactic acid in the liver.

Complementary base pairing

Specific hydrogen bonding in DNA between Adenine and Thymine (2 bonds) and Guanine and Cytosine (3 bonds).

Semi-conservative replication

DNA replication mechanism where each generated DNA molecule consists of one original parental strand and one newly synthesised strand.

Helicase

Enzyme responsible for unwinding the DNA double helix and breaking hydrogen bonds between base pairs during replication.

DNA polymerase

Enzyme that joins complementary free nucleotides via phosphodiester bonds to construct the new DNA strand during replication.

Mitosis

Division of the cell nucleus producing two genetically identical diploid daughter cells for growth, tissue repair, and asexual reproduction.

Prophase

Initial phase of mitosis where chromosomes condense, the nuclear membrane disintegrates, and spindle fibres form.

Metaphase

Stage of mitosis where chromosomes line up single file across the cell equator attached to spindle fibres by their centromeres.

Anaphase

Stage of mitosis where sister chromatids separate and are pulled to opposite poles of the cell by spindle fibres.

Telophase

Final phase of mitosis where chromosomes decondense, nuclear membranes reform around separated sets, and cytokinesis occurs.

Compensation point

The time at dawn and dusk when the rate of photosynthesis equals the rate of cellular respiration, resulting in zero net gas exchange.