Bio 121 Exam #2

Magnification

the increase of an object's apparent size by using lenses or mirrors

Resolution

the ability of a microscope to distinguish detail

contrast

The state of being noticeably different from something else when put or considered together.

light microscope

microscope that uses a beam of light passing through one or more lenses to magnify an object

electron microscope

microscope that forms an image by focusing beams of electrons onto a specimen

transmission electron microscopy

very thin slices of a specimen are used, revealing the internal structure of microbial and other cells

scanning electron microscopy

an electron microscope in which a beam of electrons is sent across the surface of a specimen and the reflected electrons are focused to produce a three dimensional image of the specimen surface.

cell fractionation

technique in which cells are broken into pieces and the different cell parts are separated

plasma membrane

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

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

chromosomes

threadlike structures made of DNA molecules that contain the genes

ribosomes

Makes proteins

nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

Nucleiod

A dense region of DNA in a prokaryotic cell.

domain bacteria

One of the three domains of life; contains prokaryotic cells that differ from archaea because they have their own unique genetic, biochemical, and physiological characteristics.

Domain Archaea

Any of various single-celled prokaryotes genetically distinct from bacteria, often thriving in extreme environmental conditions

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

organelle

specialized structure that performs important cellular functions within a eukaryotic cell

nuclear envelope

A double membrane that surrounds the nucleus in the cell

nuclear pores

structures in the nuclear envelope that allow passage of certain materials between the cell nucleus and the cytoplasm

nucleolus

Found inside the nucleus and produces ribosomes

endomembrane system

A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

vesicles

small membrane sacs that specialize in moving products into, out of, and within a cell

Rough ER

That portion of the endoplasmic reticulum studded with ribosomes.

Smooth ER

That portion of the endoplasmic reticulum that is free of ribosomes and makes lipids

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

lysosome

An organelle containing digestive enzymes

phagocytosis

Cell eating

pinocytosis

Cell drinking

Autophagy

A process in which lysosomes decompose damaged organelles to reuse their organic monomers

food vacuoles

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

contractile vacuole

saclike organelles that expand to collect excess water and contract to squeeze the water out of the cell

large central vacuole

found in plants, this organelle stores water for the cell

mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

Peroxisomes

Break down fatty acids and produce hydrogen peroxide

cytoskeleton

network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement

Microtubules

Spiral strands of protein molecules that form a tubelike structure

intermediate filaments

Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments

Microfilaments

Long, thin fibers that function in the movement and support of the cell

cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

flagella

whiplike tails found in one-celled organisms to aid in movement

motor proteins

A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.

plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent cells

tight junctions

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

Desmosomes

Anchoring junctions that prevent cells from being pulled apart

gap junctions

provide cytoplasmic channels between adjacent animal cells

which type of microscope gives scientists the highest level of magnification and resolution?

electron microscope

difference between transmission electron microscopy and scanning electron microscopy?

During the process of cell fractionation, which "size class" of subcellular structures will form pellets (come out of solution) first?

larger/heavier structures always form pellets before smaller structures

How does the presence of organelles in the cells of eukaryotes allow many of them to "afford" to be multicellular?

more efficient use of time, energy, and cell materials (due to division of labor)

Main features of prokaryotic cells

how does the plasma membrane ensure the maintenance of homeostasis?

Where are ribosomes made?

nucleolus

what do lysosomes contain that help them break down a wide variety of substances?

many hydrolases that can hydrolyze carbs, lipids, proteins, and nucleic acid molecules

Why are mitochondria and chloroplasts referred to as "semiautonomous organelles"?

What toxic byproduct do the "demolition" reactions occurring in a peroxisome create, and how does a peroxisome deal with this byproduct?

The reactions create hydrogen peroxide, which is then broken down by the peroxisome into water and oxygen gas through the use of a specific enzyme (catalase)

3 ways motor proteins use ATP to create cell movement

by "walking" along a cytoskeletal fiber, by remaining stationary while a cytoskeletal fiber is "pulled/fed along" beneath it, and by causing a cytoskeletal fiber to "bend/flex"

what 3 features does a plant cell have that an animal cell does not?

cell wall made of cellulose, chloroplasts, large central vacuole

how are animal cells held together?

extracellular matrix (ECM) mostly made of collagen protein fibers

How do plant cells communicate?

through plasmodesmata - cytoplasmic channels connecting neighboring cells

How do animal cells communicate?

direct contact (gap junctions) that connect neighboring cytosols of cells

phospholipid

a lipid that contains phosphorus and that is a structural component in cell membranes

amphipathic

having both a hydrophilic region and a hydrophobic region

selectively permeable

a property of cell membranes that allows some substances to pass through, while others cannot

fluid mosaic model

Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

peripheral proteins

The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane.

integral proteins

penetrate the hydrophobic interior of the lipid bilayer

peripheral proteins

bound to the surface of the membrane

glycolipid

a lipid with one or more covalently attached carbohydrates

glycoprotein

A protein with one or more covalently attached carbohydrates.

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

concntration gradient

the process of particles moving through a solution from an area of higher number of particles to an area of lower number of particles

passive transport

Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient

facilitated diffusion

process of diffusion in which molecules pass across the membrane through cell membrane channels

active transport

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

channel proteins

have a hydrophilic channel that certain molecules or ions can use as a tunnel

Aquaporins

A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane

carrier proteins

a protein that transports substances across a cell membrane

primary active transport

Active transport that relies directly on the hydrolysis of ATP.

secondary active transport

Form of active transport which does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport.

sodium-potassium pump

A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell.

Uniporter

A carrier protein that transports a single molecule across the plasma membrane.

Cotransport (symport)

secondary transport in same direction as Na+

antiporter

A carrier protein that transports two molecules acrss the plasma membrane in opposite directions.

receptor-mediated endocytosis

binding of ligands to receptors triggers vesicle formation

signal transduction pathway

The process by which a signal on a cell's surface is converted into a specific cellular response.

reception stage of cell signaling

the target cell's detection of a signaling molecule coming from outside the cell. A chemical signal is "detected" when the signaling molecule binds to a receptor protein located at the cell's surface or, in some cases, inside the cell

transduction stage

converts the signal to a form that can bring about a specific cellular response

Response stage of cell signaling

the transduced signal triggers a specific response in the target cell

paracrine signaling

Signal released from a cell has an effect on neighboring cells.

synaptic signaling

a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell

ligand

A molecule that binds specifically to another molecule, usually a larger one.

G-protein coupled receptors

A special class of membrane receptors with an associated GTP binding protein; activation of a G protein-coupled receptor involves dissociation and GTP hydrolysis

tyrosine kinase receptors

membrane receptors that attach phosphates to protein tyrosines

ligand-gated ion channel

A protein pore in the plasma membrane that opens or closes in response to a chemical signal, allowing or blocking the flow of specific ions.

intracellular receptors

receptors located inside the cell rather than on its cell membrane

Phosphorylation

the addition of a phosphate group to a molecule

protein kinases

enzymes that activate or inactivate other proteins by phosphorylating them

protein phosphatases

Enzymes that can rapidly remove phosphate groups from proteins.