Biology midterm 3-6chapter

Cell Theory

1. All organisms are made of cells. 2. All existing cells are produced by other living cells. 3. The cell is the most basic unit of life.

Prokaryotic Cell

Cells that do NOT have a nucleus or membrane-bound organelles (e.g., Bacteria).

Eukaryotic Cell

Cells that HAVE a nucleus and membrane-bound organelles (e.g., Plant & Animal cells).

Cytoskeleton

A network of proteins that supports cell shape, positions organelles, and assists in cell division.

Nucleus

Storehouse for genetic information (DNA) in eukaryotic cells.

Ribosomes

Organelles that link amino acids together to make proteins.

Endoplasmic Reticulum (ER)

An interconnected network of thin folded membranes that produces and processes proteins and lipids.

Golgi Apparatus

Organelle that modifies, packages, and sorts proteins for delivery to targeted destinations.

Vesicles

Small membrane-bound sacs that isolate and transport materials within the cell.

Mitochondria

Powerhouse of the cell that supplies energy (ATP) through cellular respiration.

Vacuole

A fluid-filled sac used for the storage of materials needed by a cell (very large in plant cells).

Lysosome

Organelle containing digestive enzymes to break down waste, foreign materials, and worn-out cell parts in animal cells.

Centrioles

Cylinder-shaped organelles made of short microtubules that help divide DNA during cell division in animal cells.

Cell Wall

A rigid layer that gives protection, support, and shape to plant, algae, and fungal cells.

Chloroplast

Organelle in plant cells that converts solar energy into chemical energy through photosynthesis.

Phospholipid

Molecule composed of a charged phosphate group, glycerol, and two fatty acid chains forming the cell membrane.

Fluid Mosaic Model

Model describing the cell membrane structure as flexible with embedded molecules (proteins, cholesterol, carbohydrates).

Selective Permeability

Property of the cell membrane that allows only certain materials to pass across it.

Receptor

A protein that detects a signal molecule (ligand) and performs an action in response.

Intracellular Receptor

Receptor inside the cell that binds to small or nonpolar ligands that CAN cross the cell membrane.

Membrane Receptor

Receptor bound in the membrane that binds to ligands that CANNOT cross the cell membrane.

ATP (Adenosine Triphosphate)

High-energy molecule that transfers energy from the breakdown of food molecules to cell processes.

ADP (Adenosine Diphosphate)

Lower-energy molecule that can be converted into ATP by the addition of a phosphate group.

Photosynthesis

Process that captures energy from sunlight to make sugars that store chemical energy.

Chlorophyll

A molecule in chloroplasts that absorbs light energy for photosynthesis.

Thylakoid

Coin-shaped, membrane-enclosed compartments inside chloroplasts where light-dependent reactions occur.

Stroma

The fluid that surrounds the thylakoids inside a chloroplast where light-independent reactions (Calvin cycle) occur.

Light-Dependent Reactions

Part of photosynthesis that captures energy from sunlight; takes place in thylakoids and produces oxygen and ATP.

Light-Independent Reactions

Part of photosynthesis that uses ATP from light reactions to make sugar (glucose); takes place in the stroma.

Cellular Respiration

Process that releases chemical energy from sugars and other carbon-based molecules to make ATP when oxygen is present.

Aerobic Process

A process that REQUIRES oxygen to take place (e.g., Cellular Respiration).

Anaerobic Process

A process that does NOT require oxygen to take place (e.g., Glycolysis, Fermentation).

Glycolysis

Anaerobic process in cytoplasm that splits glucose into two three-carbon molecules and produces 2 ATP.

Krebs Cycle

Process in mitochondrial matrix that breaks down carbon molecules to produce energy carriers (NADH, FADH2) and CO2.

Electron Transport Chain (ETC)

Process in inner mitochondrial membrane that uses high-energy electrons to produce a large amount of ATP and H2O.

Fermentation

An anaerobic process that allows glycolysis to continue making ATP when oxygen is not present.

Lactic Acid Fermentation

Type of fermentation occurring in muscle cells that produces lactic acid as a byproduct.

Alcoholic Fermentation

Type of fermentation occurring in yeast that produces alcohol and carbon dioxide.

Chromosome

One long continuous thread of DNA that consists of numerous genes along with regulatory information.

Histones

Group of proteins that DNA wraps around to condense into chromatin.

Chromatin

The loose combination of DNA and proteins present during interphase.

Chromatid

One half of a duplicated chromosome (sister chromatids are identical copies).

Centromere

Region of a condensed chromosome that holds together the two sister chromatids.

Telomere

Structures at the ends of DNA molecules that prevent chromosomes from sticking to each other and prevent gene loss.

Mitosis

Division of the cell nucleus and its contents (Prophase, Metaphase, Anaphase, Telophase / PMAT).

Cytokinesis

Division of the cell cytoplasm, resulting in two genetically identical daughter cells.