Cell Biology Lecture Notes

Flashcards based on cell biology lecture notes, covering cell theory, prokaryotic and eukaryotic cells, organelles, membrane structure and function, transport mechanisms, and cell structures.

Cell

The smallest unit of life that can function independently and perform all the necessary functions of life.

Cell Theory

All living organisms are made up of one or more cells, and all cells arise from other, preexisting cells.

Eukaryotic Cells

Cells with a nucleus that contains the cell’s DNA.

Prokaryotic Cells

Cells that do not have a nucleus; their DNA is free in the cytoplasm. Includes Bacteria and Archaea.

Plasma Membrane (Prokaryotes)

Encloses cell contents: DNA, ribosomes, and cytoplasm in prokaryotic cells.

Cytosol (Prokaryotes)

Jelly-like fluid inside prokaryotic cells.

DNA (Prokaryotes)

One or more circular loops containing genetic information in prokaryotic cells.

Ribosome (Prokaryotes)

Granular body in the cytoplasm that converts genetic information into protein structure in prokaryotic cells.

Cell Wall (Prokaryotes)

Protects and gives shape to the cell in prokaryotes.

Capsule (Prokaryotes)

Protective outer coating in prokaryotes.

Pilus (Prokaryotes)

Hair-like projection that helps cells attach to other surfaces and sometimes plays a role in DNA transfer in prokaryotes.

Flagellum (Prokaryotes)

Whip-like projection that aids in cellular movement in prokaryotes.

Typical Eukaryotic Cell Features

DNA contained in a nucleus, cytoplasm contains specialized structures called organelles, and larger than prokaryotes.

Typical Prokaryotic Cell Features

No nucleus, internal structures mostly not organized into compartments, and much smaller than eukaryotes.

Endosymbiosis Theory

Explains the presence of chloroplasts and mitochondria in eukaryotes, suggesting they originated from free-living prokaryotic cells.

Which organelles does the endosymbiosis theory explain the origin of?

Mitochondria and chloroplasts.

Invagination

Theory that explains the origin of some eukaryotic organelles through the infolding of the plasma membrane.

Functions of the Plasma Membrane

Holds contents of cell in place, takes in food and nutrients, aids in building and exporting molecules, and allows interactions with the environment and neighboring cells.

Phospholipid Bilayer

A bilayer forms because the hydrophobic tails face toward one another and the polar heads face away to separate the contents of the cell from the environment.

Receptor Proteins

Proteins that bind to chemicals in the cell’s external environment to regulate processes within the cell

Recognition Proteins

Proteins that give each cell a “fingerprint” for determining self vs. nonself

Transport proteins

Proteins that help polar or charged substances cross the plasma membrane

Membrane enzymes

Proteins that accelerate chemical reactions on the plasma membrane’s surface

Cystic Fibrosis

Genetic defect in a membrane protein that controls the flow of chloride ions, resulting in multiple damaging effects.

Beta-blockers

Block the binding of adrenaline to cell membranes, preventing increases in heart rate and blood pressure.

Tight Junctions

Form a water-tight seal between cells.

Desmosomes

Act like Velcro and fasten cells together.

Gap Junctions

Act like secret passageways and allow materials to pass between cells.

Passive Transport

Movement of molecules across a membrane without energy input from the cell, requiring a concentration gradient.

Simple Diffusion

No membrane protein required for transport.

Facilitated Diffusion

Channel or carrier protein required for transport.

Osmosis

Diffusion of water through channel proteins (aquaporins), moving from areas of higher water concentration to areas of lower water concentration.

Tonicity

The relationship between the concentration of solutes inside the cell and solutes outside the cell (in solution).

Isotonic

Concentration of solutes outside the cell is equal to the concentration inside the cell.

Hypotonic

Concentration of solutes outside the cell is lower than the concentration inside the cell.

Hypertonic

Concentration of solutes outside the cell is higher than the concentration inside the cell.

Active Transport

Movement of molecules into and out of a cell that requires the input of energy.

Primary Active Transport

The protein uses ATP directly to move molecules.

Secondary Active Transport

Proteins obtain energy in an indirect method.

Endocytosis

Moving particles into a cell by engulfing large particles with the plasma membrane.

Phagocytosis

Solid particles are engulfed.

Pinocytosis

Liquid is engulfed.

Receptor-mediated Endocytosis

Specific types of particles are engulfed.

Exocytosis

Export of particles out of a cell.

Nucleus

The cell’s genetic control center.

Structure of the Nucleus

Nuclear membrane (2 bilayers) with pores, Chromatin (DNA with proteins attached), and Nucleolus (where ribosomes are made).

Cytoskeleton

Gives animals' cells their shape, provides pathways for movement of organelles and molecules inside the cell, gives ability for cell movement.

Cilia

Short projections that beat swiftly to move fluid along and past a cell.

Flagella

Long, microtubule-based structures that move cells through their environment.

Mitochondria

Convert carbohydrates, lipids, and proteins into usable energy, carbon dioxide, and water.

Lysosomes

Contain acidic fluid and many enzymes to break down and recycle waste macromolecules or particles taken in by phagocytosis.

Functions of the Endomembrane System

Produces and modifies molecules to be exported to other parts of the organism, breaks down toxic chemicals and cellular by-products.

Rough Endoplasmic Reticulum (ER)

Modifies proteins that will be shipped to other locations in the endomembrane system, the cell surface, or outside the cell.

Smooth Endoplasmic Reticulum (ER)

Synthesizes lipids such as fatty acids, phospholipids, and steroids; detoxifies molecules such as alcohol, drugs, and metabolic waste products.

Golgi Apparatus

Processes and packages proteins, lipids, and other molecules for export to other locations inside and outside the cell.

Cell Wall (Plants)

Provides additional protection and support for plant cells, made of cellulose.

Plasmodesmata

Tubelike channels that connect plant cells to each other, enabling them to communicate through the walls.

Vacuoles

Multipurpose storage sacs for cells, including nutrient storage, waste management, predator deterrence, sexual reproduction, and physical support.

Chloroplasts

The site of photosynthesis, where light energy is converted into chemical energy of food molecules.