ap biology

Magnification

the ratio of an object's image size to its real size

Resolution

a measure of the clarity of an image

minimum distance two points can be separated and still be distinguished as two points

Light Microscope

An optical instrument with lenses that refract (bend) visible light to magnify images of specimens.

Can magnify 1000x

0.2um resolution

Electron Microscope

A microscope that uses magnets to focus an electron beam on or through in specimen resulting in resolving power a thousandfold greater than that of a light microscope

Transmission Electron Microscope

An electron microscope used to study the internal structure of thin sections of cells

Scanning Electron Microscope

An electron microscope used to study the fine details of cell surfaces

3 Jobs of the Cell

make energy, make proteins, make more cells

Organelles

Membane-enclosed compartments

Eukaryotes have this, prokaryotes don't

Plasma Membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

Cytoplasm

The contents of the cell, exclusive of the nucleus and bounded by the plasma membrane.

Ribosomes

A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus.

Prokaryotic Cell

Type of cell lacking a membrane-encolosed nucleus and membrane-enclosed organelles

Bacteria and archea

Contain a singular chromosome

Nucleoid

A dense region of DNA in a prokaryotic cell.

Plasmid

a small, circular, double-stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome

mostly found in prokaryotic cells, sometimes found in eukaryotic cells

Eurkaryotic Cells

Type of cell with a membrane-enclosed nucleus and membrane-enclosed orgnalles

Organisms include plants, fungi, and animals

Cell Membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

Separates cell from outside

Recognizes signals from other cells

Contains receptor modules (proteins that receive signals)

Vesicles

Sacs made of membrane in the cytoplasm that moves material around cell for storage

Smaller and more specialized that valeocules

Can fuse with other membranes in cell system

Vacuole

Membrane-bounded vesicle whose function varies

Central Vacuole

A membranous sac in a mature plant cell with diverse roles in reproduction, growth, and development.

Largest compartment in a plant cell

Purpose mostly storage

Food Vacuole

A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell.

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

Contractile Vacuole

A membranous sac that helps move excess water out of certain freshwater protists.

Lysosomes

A membranous-enclosed sac of digestive enzymes found in cytoplasm of animal cells and protists

Breakdown ingested substances, cell macromolecules, and damage organelles for recycling

Functions best in acidic environment

Made by rough ER then transferred to Golgi Apparatus

Mitochondria

Organelle in eukaryotic cells that serves as the sight for cellular respiration

Extracts energy from sugars, fats, and other fuelds, creating ATP

Have two membranes, separates innermost space from cytosol

Inner membrane has folding

Chloroplast

An organelles found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water

Two membranes, the same as the mitochondria

Membrane proteins here and in mitochondria made by free ribosomes in cytosol

Energy from sunlight

Green pigment to plant

Nucleus

Chromosome-containing organelle of a eukaroytic cell

Control center of th cell

Protects DNA

Structure of the Nucleus

Nuclear envelope, nucleolus, chromosomes

Nuclear Envelope

Double membrane that surrounds nucleus of the cell, separating it from the cytoplasm

Nucleolus

Dense spherical structure inside nucleus of eukaryotic cell, involved in creation of ribosomes

Synthesizes and process rRNAA to combine with proteins and form subunits of ribosome

Chromosomes

Structures in cells that contain DNA

Endoplasmic Reticulum

AAn extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

Serves as production and packaging system

Helps complete protein after ribosome built them

Involved in protein synthesis, lipid metabolism

Smooth Endoplasmic Reticulum

The portion of the endoplasmic reticulum that lacks attached ribosomes

Synthesis of lipids, metabolism of carbohydrates, calcium, detoxification of drugs and poisons

Rough Endoplasmic Reticulum

The portion of the endoplasmic reticulum that contains attached ribosomes

Aids in synthesis of secretory and other proteins from bound ribosomes, adds carbohydrates to glycoproteins, makes new membrane

Golgi Apparatus

An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products

UPS Headquarters

Ships proteins in vessicles

Selective Permeability

The property of a membrane that allows some substances to pass through, but not others

Important in homeostasis

Help control chemical reaction in cell

Plasma Membrane is composed of...

Phospholipids, proteins, cholesterol, carbohydrates

What role does phospholipid play in the membrane?

Main part of the cell membrane

Ampipathic

Molecule that has both hydrophobic and hydrophilic regions

What role do proteins play in the plasma membrane?

Responsible for enzymatic activity and are the big block in the membrane

What role does cholesterol play in the plasma membrane?

Connects phospholipid

What role does carbohydrates play in the plasma membrane?

Chain attached to either protein enzyme or phospholipid

Glycolipid

a lipid with one or more covalently attached carbohydrates

Glycoprotein

A protein with one or more carbohydrates covalently attached to it.

Fluid Mosaic Model

The currently accepted model of cell membrane structure, which envisions the membrane was a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipid

How is the plasma membrane linked?

Linked my hydrophobic interactions

What do proteins determine in their relation to the membrane?

Protein determines membrane's specific function

Peripheral Proteins

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.

Often serve as enzymes or in signal transduction

Integral Proteins

A protein permanently attached within plasma membrane

Perform various functions like transporting ions or molecules across the membrane

Penetrate through hydrophobic core

Six functions of membrane proteins

1. Transport

2. Receptors for signal transduction

3. Attachment to cytoskeleton and extracellular matrix

4. Enzymatic activity

5. Intercellular joining

6. Cell-cell recognition

Transport

Integral membrane proteins involved in moving ions, small molecules, or macromolecules, such as nother protein, across a biological membrane.

Enzymatic

A protein built into membrane may be an enzyme with its active site in adjacent solutions

Signal Transduction

A membrane protein (receptor) may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The external messenger (signaling molecule) may cause the protein to change shape, allowing it to relay the message to the inside of the cell, usually by binding to a cytoplasmic protein.

Cell-cell Recognition

some glycoproteins serve as identification tags that are specifically recognized by other cells

Intercellular Joining

membrane proteins of adjacent cells may hook together in various kinds of junctions, such as gap junctions or tight junctions

Attachment to cytoskeleton and ECM

Microfilaments or other elements of the cytoskeleton may be noncovalently bound to membrane proteins, a function that helps maintain cell shape and stabilizes the location of certain membrane proteins. Proteins that can bind to ECM molecules can coordinate extracellular and intracellular changes.