AP BIO Unit 2 - Chapter 6

Light Microscopes

Light microscopes are commonly used in classrooms. Living cells can be examined; can only magnify effectively to about 1,000 times the real size of a specimen.

Scanning Electron Microscopes

Studies the surface of cells, looks at the outside of the cell, much more powerful, and use electrons to see an image rather than light; the researcher views the image on a screen

Transmission Electron Microscopes

studies the insides of the cell; the preparation kills the cells and therefore cannot be used on living cells

Cell Fractionation

This is a process that allows scientists to study different parts of the cell, almost blending the cells and then using centrifugation. It separates the different parts of the cell based on density, and then those separated sections can be tested for their functions

All cells have…

plasma membrane, cytosol, ribosomes, chromosomes

Prokaryotic Cells

These cells are a lot simpler and smaller and lack organelles; the chromosomes are confined in the nucleoid region.

Eukaryotic Cells

these cells are larger and more complex, have membrane-bound organelles and a nucleus, ex. plant and animal cells

Endosymbiotic Theory

evolutionary theory that explains the origin of eukaryotic cells from prokaryotes, that several key organelles of eukaryotes originated as a symbiotic relationship between separate single-celled organisms (bigger one engulfed the other).

Plasma Membrane

determines what can come in and go out of the cell, made up of a phospholipid bilayer and has proteins throughout it

Limits of cell size

If a cell gets too big, it will not be able to transport out waste quickly enough, and the cell will be poisoned. As a cell increases in size, its volume increases faster than its surface area. So, smaller objects have a higher ratio of Surface Area to Volume than larger cells.

Nucleus

Control center of the cell; contains most of the DNA (genes) of the cell.

Nucleolus

Part inside the nucleus that makes rRNA (makes ribosomes)

Nuclear Envelope

Double membrane that surrounds the nucleus; it has pores so that the RNA can get out

Nuclear Lamina

a network of protein filaments INSIDE the nucleus used to help with the structure

Chromatin

uncoiled chromosomes…for most of the cell cycle the DNA is in this form (they coil up into chromosomes before cell division)

Free Ribosomes

are NOT attached to the ER and synthesize proteins that function within the cytosol

Bound Ribosomes

attached to ER or nuclear envelope; synthesize proteins that are inserted into membranes or that are secreted from the cell

Endomembrane System

Endoplasmic Reticulum (ER)

the ER is connected to the nuclear envelope and has a very folded structure to increase the surface area; it accounts for more than HALF the membranes in a eukaryotic cell. There are two continuous parts to the ER – Smooth and Rough

Smooth ER

lacks ribosomes; function - makes lipids (hormones, steroids); detoxifies drugs and alcohol, breaks down carbs, stores calcium ions

Rough ER

lined with ribosomes; function - makes secretory proteins and makes membranes; LOTS in cells that secrete proteins

Golgi

packages, modifies (from ER or own), and secretes substances from cell; has a “receiving” side (cis) and a “shipping” side (trans).

Lysosomes

only in animal cells, sacs of enzymes, can digest and recycle old parts of the cell (autophagy); can digest/destroy dangerous things that are taken into cell (phagocytosis); and can perform apoptosis

Vacuoles in animals

used mostly for storage, much smaller and more numerous – food vacuoles are used with lysosomes to digest food, and contractile vacuoles (found mostly in single celled animals) get rid of excess water

Vacuoles in plants

a large central organelle that stores water, waste, and enzymes, can increase or decrease turgor pressure, surrounded by tonoplast (membrane)

Mitochondria

site of cellular respiration, use oxygen to generate ATP by extracting energy from sugars, fats, and other fuels; has a double membrane with inner membrane highly folded (cristae) to increase the surface area

Chloroplasts

found in plants and algae, site of photosynthesis; they convert solar energy to chemical energy by absorbing sunshine and using it to synthesize new organic compounds such as sugars from CO2 and H2O

Peroxisomes

have a variety of functions in cells, produce hydrogen peroxide as a byproduct, then immediately break it down into water and oxygen – help detoxify alcohol in the liver

Cytoskeleton

the structural support in animal cells, helps anchor organelles and aids in cell movement, made of microtubules, microfilaments, and intermediate filaments

Microtubules

hollow rods that make up part of the cytoskeleton; made of protein tubulin; helps organelles move around, cilia and flagella are also made of microtubules

Centrosomes and Centrioles

located near the nucleus and makes microtubules; organelles that are found within centrosomes in animal cells - help with cell division

Cilia

made of microtubules, almost looks like fur, lines the cell and sweeps substances away from the surface of the cell, use motor proteins to move

Flagella

made of microtubules, looks like a tail and helps the cell move, uses motor proteins to function

Basal Body

anchors cilia and flagella in the cell; structure is identical to a centriole

Microfilaments

made of the protein actin, are solid rods and are thin, designed to bear tension

Intermediate filaments

more permanent, down break down to reassemble as much, have a variety of functions in the cell

Primary Cell Wall

starts as thin and flexible, develops from the cell plate after cell division; once the plant matures, it hardens to be more supportive

Secondary Cell Wall

this is found under the primary cell wall to strengthen it; it is not in every plant; it is very strong

Middle Lamella

this “glues” plant cells together; it is found between the cell wall of one and the cell wall of another

Cell Walls

protect the cell, maintains its shape, prevents excessive water uptake, and supports the plant against gravity

Extracellular matrix

structure found outside of animal cells, provides support, adhesion, movement, and regulation

Plasmodesmata

channels in cell walls of plants, allows substances to get from one plant cell to the next

Tight junctions

in animals, fusing of membranes of adjacent cells; prevents leakage of fluid

Desmosomes/Anchoring Junctions/Adhesion Junctions

animal, holds cells together in strong sheets

Gap Junctions/Communicating Junctions

holes between cells that allow cellular substances to pass through; similar to plasmodesmata, very important in development for chemical signaling