NVCC BIO 141 Chapter 3

Name the three main parts of a eukaryotic cell and list the general function of each

Plasma Membrane: provides structural support by physically isolating cell from surroundings

Cytoplasm: holds Cytosol, Organelles, and Cytoskeleton

Nucleus: has nuclear envelope; contains DNA + primary location of RNA production

List the four basic processes carried out by all cells

Cell Metabolism

Transport of Substances

Communication

Cell Reproduction

Describe the four components of the cytoplasm

Cytosol: fluid portion

Inclusions: clusters of storage Bodies

Organelles: compartmentalizing cell's function

Cytoskeleton: network of protein filaments

Describe the structure of the plasma membrane according to the fluid mosaic model

Structure with multiple parts whose arrangement is dynamic; phospholipids shift continually and switch with adjacent phospholipids to do so rapidly

State the organic molecule (lipids or proteins) that forms the major component of the plasma membrane

Phospholipids

Differentiate between transmembrane, integral and peripheral proteins

Transmembrane: reach both sides of membrane

Integral: span entire width of membrane

Peripheral: only on one side of membrane; some anchored in place, others float within phospholipid layer

Describe the six different functions of proteins in the cell membrane

Protein Channels: allow certain substances to cross membrane

Carrier Proteins: transport substances in/out

Receptors: triggers changes in cell

Enzyme: vital to membrane structure/function

Structural Support

Linking Adjacent Cells: holds cells as tissues

List the three different lipid components of the cell membrane and their role

Cholesterol: stabilizes structure of membrane

Glycolipids: cell regulation

Phospholipids: cell membrane

Name the two major membrane transport processes and distinguish between the two

Passive Transport: requires no net expenditure of energy from cell

Active Transport: requires cells to expand energy in the form of ATP

Describe the characteristics of simple diffusion

involves nonpolar solutes that pass straight through phospholipid bilayer without assistance from membrane protein

Give examples of molecules that move by simple diffusion

Hydrocarbons

Lipids

Gases like O2/CO2

Differentiate between simple diffusion and facilitated diffusion

Facilitated Diffusion: involves charged/polar solutes that need help of membrane protein

Simple Diffusion does not need help

State the two types of facilitated diffusion and give one example for each

Ions through a Channel - Na+ leak channels

Polar/Ionic compounds with a carrier - Glucose carriers prevent loss of glucose in urine

Define osmosis and list two ways water crosses cell membranes

movement of solvent across a selectively permeable membrane

Water can cross via Aquaporins (water channels) and between phospholipids in the membrane

Explain how osmosis differs from simple diffusion

Diffusion is movement of molecules, Osmosis is movement of water

Define osmotic pressure and hydrostatic pressure

Osmotic Pressure: pressure that must be applied to a solution to prevent water form moving into it by osmosis

Hydrostatic Pressure: force that water exerts on wall

Define tonicity

way to compare solute concentrations of 2 solutions; determined by solutes that aren't freely crossing the membrane

Define isotonic, hypertonic, and hypotonic solutions

Isotonic: concentration is equal inside to outside; no net movement

Hypertonic: concentration greater outside the cell; water leaves cell which shrivels

Hypotonic: concentration is greater inside the cell; water enters cells, which swells/may burst

Name two different types of active transport

Primary Active Transport and Secondary Active Transport

Define primary active transport

pump binds a solute and transports in against the concentration gradient using the energy from hydrolysis of ATP

State the source of energy that drives primary active transport

Primary active transport uses energy derived directly from the breakdown of ATP

Explain the function of the sodium-potassium pump in relation to the movement of those ions

1) pumps bind 3 sodium ion from the cytosol

2) ATP hydrolyzed, phosphate bind to pump and the pump changes shape

3) pump releases 3 Na+ to ECF, bind 2 K+

4) Phosphate detaches, pump changes back to normal shape

5) Pump releases 2 K+ into cytosol

Define secondary active transport

uses ATP indirectly, active transport of one substance is coupled with the passive transport of a second substance

State the source of energy that drives secondary active transport in connection to primary active transport

kinetic energy of one substance moving down its concentration gradient provides the power to pump the other substance across its concentration gradient

Explain an example of secondary active transport utilizing a symport carrier protein

Symport carrier protein uses potential energy of Na+ gradient to power transport of glucose

Define resting membrane potential in relation to the distribution of sodium and potassium across the cell membrane

Resting Membrane Potential: value of membrane potential when cell is at rest, not stimulated, or inhibited by other factor

Define vesicular transport

transport of large substances across the plasma membrane by vesicle (a membrane-bound sac filled with materials)

State whether vesicular transport is an active or passive process

Active Process

Differentiate between endocytosis and exocytosis

Endocytosis: molecules taken into the cell

Exocytosis: molecules release from the cell

List and describe the two types of endocytosis

Phagocytosis: cells ingest large particles; only phagocytes can do this

Pinocytosis: cellular ingestion of droplets of the ECF; provides smaller transport vesicle; brings nutrients

Describe the structure and function of Mitochondrion

double membrane; inner membrane folded into cristae; has own DNA/ribosomes

synthesizes the majority of the cell's ATP

Describe the structure and function of Peroxisome

membrane-enclosed; similar to large vesicles

detoxifies chemicals via oxidation; metabolizes fatty acids; synthesizes certain phospholipids

Describe the structure and function of Ribosome

2 subunits of protein/rRNA; not membrane-enclosed

synthesizes proteins

Describe the structure and function of Rough Endoplasmic Reticulum

series of saclike membranes closing the ER lumen; surface studded with ribosomes

modifies/folds proteins; manufactures and assembles most components of plasma membranes

Describe the structure and function of Smooth Endoplasmic Reticulum

series of tubular membranes enclosing the ER lumen; surface does not contain ribosomes

stores calcium ions/synthesizes lipids, detoxifies certain substance

Describe the structure and function of Golgi Bodies

stack of flattened, membrane-enclosed sacs

sorts/modifies/packages proteins and other substances

Describe the structure and function of Lysosome

membrane-enclosed structure with digestive enzymes; similar to large vesicles

digests damaged organelles/products brought into the cell by endocytosis; recycles damaged organelles

List components of the endomembrane system and state their function

Synthesize, modify, package molecules produced by the cell

(plasma membrane, endoplasmic reticulum, Golgi apparatus, lysosomes, and nuclear envelope)

List four functions of the cytoskeleton

gives a cell its characteristic shape and size

supporting plasma/nuclear membranes/organelles

function in movement

performing specialized functions in different cell types

Describe structure and function of the nucleus

ensures that multiple components of cell function together optimally for the cell to survive

1) nuclear envelope with nuclear pores

2) DNA/associated proteins

3) nucleolus

Describe structure and function of the nucleolus

ribosome factory; where ribosome are assembled enclosed by large aggregate of proteins, DNA, and RNA

Differentiate between chromatin and chromosomes

Chromatin: one extremely long DNA strand + associated proteins

Chromosomes: chromatin coiled together during cell division

List the number of chromosomes in a human cell

23 sets (46 total)

Explain the steps of protein synthesis, from DNA to RNA to protein

DNA

(Transcription)

mRNA

(Translation)

Protein

Define a gene and mutation of a gene

Gene: segment of DNA

Mutation: change in DNA from mistake in DNA copy or due to mutagens

Explain the genetic code

list of which amino acids is specified by each possible DNA triplet

Define transcription and explain where it occurs in the cell

1) Initiation

1a) Transcription begins when transcription factors bind to the promoter

1b) RNA polymerase binds to the promoter as well, and a segment of DNA unwinds

2) Elongation: RNA polymerase builds a complementary mRNA transcript with three nucleotides

3) Termination: transcription ends when the end of the gene is reached, and the mRNA transcript is released

(all in nucleus)

Define introns and exons in the pre-mRNA

Intron: does not code

Extron: actual code for protein

List the three types of RNA and explain the function of each of the three types

Messenger (mRNA): carries instructions for how to synthesize protein

Transfer (tRNA): adapter to bring specific amino acid to mRNA codon

Ribosomal (mRNA): specific type of RNA for forming ribosomes

Name the type of RNA formed after completion of transcription

mRNA

Define a codon and anticodon

Codon: sequence of 3 nucleotides complementary to a specific DNA triplet

Anticodon: sequence of 3 nucleotides complementary to a specific mRNA codon

Define translation and explain where it occurs in the cell

1) Initiation: translation begins when an initiator tRNA binds the mRNA start codon in the ribosome

2) Elongation

2a) Another tRNA binds to the open A-site

2b) first amino acids joined to 2nd amino acid by peptide bond

2c) ribosome moves down to next mRNA codon, the empty tRNA exits, and the new tRNA comes in

3) Termination: Translation ends when the ribosome reaches the stop codon and the polypeptide released

(all in ribosomes in cytosol)

Explain the two stages of the cell life cycle

Interphase: cell grows/prepares for division

M Phase: cell division

List and describe the events that occur during the three subphases of interphase

G1 Phase: cell preforms normal metabolic function; growing and carrying out rapid protein synthesis

S Phase: DNA synthesis takes place

G2 Phase: another period of cellular growth; proteins necessary for cell division are rapidly produced and centrioles are duplicated

List and describe the events that occur during the two subphases of the M phase

Mitosis: division of genetic material between 2 daughter cells

Cytokinesis: division of cell's protein, organelles, and cytosol between the daughter cells

Name the major enzyme involved in DNA replication

DNA polymerase

List and describe the four phases of mitosis

Prophase: chromatin condenses so sister chromatids are visible; nucleolus disperses; mitotic spindle forms and in late prophase spindle fibers attach to sister chromatids; 2 centriole pairs separate/begin migrating to opposite poles of cell; nuclear envelope breaks

Metaphase: spindle fibers pull sister chromatids to align to equator cell

Anaphase: sister chromatids separate as spindle fibers shorten; daughter chromosomes are pulled to opposite poles; cell elongates; cytokinesis starts

Telophase/Cytokinesis: nuclear envelope reassembles; nucleoli reform; chromosomes return to chromatin; cleavage-furrow forms; daughter cells separate

Define the cleavage furrow and explain how it is involved in cytokinesis

indentation along cell equator which pinches cell into two

Define apoptosis and give one example

"cellular suicide"; cell that doesn't pass checkpoints and cannot be repaired

development of feet/hands are webbed but cells there 'die' to separate fingers/toes