principles of bio ch 4

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

eurkaryotic cell

A multi-cellular organism with a nucleus and membrane-bound organelles

three domains

Bacteria, Archaea, Eukarya

All prokaryotes

lack a membrane bound nucleus

archaeal cell structure is...

relatively poorly understood

most bacteria contain several structural similarities:

• plasma membrane

• cytoplasm

• a single chromosome (DNA)

• ribosomes (DNA)

• ribosomes (synthesize proteins)

• stiff cell wall (peptoglycan)

• capsule (polysaccharide)

most prokaryotes have one...

supercoiled circular chromosome in the nucleoid region

other structures contained in prokaryotic cytoplasm:

• ribosomes

• -some have internal photosynthetic membranes

• some have organelles

eukaryotes are _______ than most prokaryotes

larger

the large size of the eukaryotic cell =>

limited speed of molecular diffusion within the cell

(-This problem is partially solved by breaking up the large cell volume into several smaller membrane-bound organelles.

The compartmentalization of eukaryotic cells offers two primary advantages:

• Separation of incompatible chemical reactions

• Increasing the efficiency of chemical reactions

Four key differences between eukaryotic and prokaryotic cells

• eukaryotic chromosomes are found inside a membrane-bound compartment called a nucleus

• -eukaryotic cells are often much larger

• eukaryotic cells contain extensive amounts of internal membrane

• eukaryotic cells feature a diverse and dynamic cytoskeleton

which of the following would NOT be found in prokaryotic cells?

nucleus

if you were a prokaryotic cell, you would be lacking _____

mitochondria to generate ATP

you are examining a cell from a crime scene using an electron microscope. It contains ribosomes, DNA, a plasma membrane, a cell wall, and mitochondria. What type of cell is it?

plant cell

cytoplasm

• cell's entire region between the plasma membrane and the nucleus

• 70-80 percent water (but semi-solid)

• organelles suspended in the gel-like cytosol

• cytoskeleton

• -various chemicals

The nucleus is surrounded by a double membrane called?

nuclear envelope

the nucleus has a distinct region called..

nucleolus

function of nucleus

• information storage and processing

• contains the cell's chromosomes

• Ribosomal RNA synthesis in the NUCLEOLUS
  RNA synthesis

nuclear envelope has..

a "double" phospholipid bilayer, and is continuous with the ER

nuclear lamina

fibrous proteins that form a lattice-like sheet, linked to the inside surface of the nuclear envelope

nucleoplasm

semi-solid fluid inside the nucleus that contains the chromatin and nucleolus

nuclear pores

thousands of openings in the nuclear envelope. function as doors into and out of nucleus

ribosome structure

non-membrane bound dense particle of rRNA and protein composed of 2 distinct subunits (small and large)

• can be attached to the rough ER or free in the cytosol

ribosome function

• protein synthesis

• ribosomes are particularly abundant in cells that synthesize large amounts of protein

Rough ER structure

• a network of membrane-bound tubes and sacs studded with ribosomes

• interior is called the lumen

• continuous with the nuclear envelope

Rough ER function

• ribosomes associated with the rough ER synthesize proteins

• new proteins are folded and processed in the rough ER lumen

Smooth ER structure

lacks the ribosomes associated with the rough ER

Smooth ER function

• enzymes within the smooth ER may synthesize fatty acids and phospholipids, or break down poisonous lipids

• reservoir for Ca^2+ ions

golgi apparatus structure

formed by a series of stacked flat membranous sacs called cisternae

Golgi apparatus function

-Processes, sorts, and ships proteins synthesized in the rough ER
membranous vesicles carry materials to and from the organelle

peroxisomes structure

globular organelles bound by a single membrane

peroxisomes function

-center of oxidation reactions

• break down fatty acids and amino acids

• -detoxify poisons

glyoxysomes

-specialized peroxisomes found in plants

• packed with fat-oxidizing enzymes

• convert stored fats into sugars

vacuoles structure

• large membrane-bound structures found in plants and fungi

• some contain digestive enzymes

vacuoles function

-some are specialized for digestion

-most are used for storage of water and/or ions to help the cell maintain its normal volume

Mitochondria structure

• have two membranes; the inner one is folded into a series of sac-like cristae. the solution inside the cristae is called the mitochondrial matrix

• mitochondria have their own DNA and manufacture their own ribosomes

mitochondria function

• cellular respiration/ ATP production

chloroplasts structure

• most plant and algal cells have these, they have a double membrane and contain their own DNA, like mitochondria

thylakoids

membrane-bound, flattened vesicles, which are stacked into piles called grana. found in chloroplasts

stroma

fluid portion of the chloroplast; outside of the thylakoids

chloroplasts function

convert light energy to chemical energy- photosynthesis

lysosomes structure

• single membrane bound structures containing approximately 40 different digestive enzymes

• found in animal cells

lysosomes function

digestion and waste processing

Phagocytosis

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

cell wall

fungi, algae, and plants have a stiff outer _______ that protects the cell

cellulose

in plants and algae, the cell wall's primary component

chitin

in fungi, the cell wall's primary component

Cytoskeleton

composed of protein fibers, gives the cell shape and structural stability, and aids cell movement and transport of materials within the cell

in essence, the cytoskeleton...

organizes ALL OF the organelles and other cellular structures into a cohesive whole

function

an organelle's membrane and its enzymes correlate with its...

cell function

cell structure correlates with...

endomembrane system

a group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins

parts of the endomembrane system

• nuclear envelope

• -lysosomes

• vesicles

• sER and rER

• plasma membrane

ions, ATP, amino acids, and other small molecules diffuse randomly throughout the cell, but....

the movement of proteins and other large molecules is energy demanding and tightly regulated

secretory pathway hypothesis

proposes that proteins intended for secretion from the cell are synthesized and processed in a highly prescribed set of steps

proteins are packaged into _____ when they move

vesicles

new cisternae form at the

cis face

old cisternae break off from the

trans face

protein products enter the golgi apparatus at the ______ and pass through cisternae containing enzymes for __________ before exiting on the far side ( ______) of the golgi

cis face, attaching specific carbohydrate chains, trans face

It has no ribosomes

why is the smooth ER unable to synthesize proteins?

ribosomes

which of the following is/are too small to have been discovered before invention of the electron microscope?

FALSE

the golgi apparatus contains enzymes known as proteases that are responsible for proteolysis" T or F?

rough ER and golgi apparatus

glycosylation of proteins take place in?

cytoskeleton elements

microfilaments, intermediate filaments, microtubules

the cytoskeleton

• complex and dynamic network of fibers

• maintain the cell shape by providing structural support

• alter the cell's shape or move the cell itself

• transport materials into the cell

actin filaments (microfilaments)

-smallest cytoskeletal elements

-Formed by the polymerization of individual actin molecules

• grouped together into long bundles or dense networks

• usually found just inside the plasma membrane

• help define the cell's shape

movement

actin filaments can also be involved in ________ by interacting with the motor protein myosin

cell movements caused by actin-myosin interactions

• muscle contraction

• cell crawling

• cytokinesis

• cytoplasmic streaming

intermediate filaments

• defined by size

• many types exist

• provide structural support that form a flexible skeleton shape the cell surface and hold the nucleus in place

• they are NOT involved in movement

microtubule structure

• large, hollow tubes made of tubulin dimers

• have polarity, are dynamic

• originate from the microtubule organizing center and grow outward, radiating throughout the cell

• in animal cells, the centrosome ( 2x centrioles) is the microtubule organizing center

microtubule function

• stability, movement, structural framework for organelles

• can act as "railroad tracks", transport vesicles move through the cell along theses microtubule tracks in an energy-dependent process

ATP and kinesin

microtubules require ____________ for vesicle transport to occur

kinesin

a motor protein that converts chemical energy in ATP into mechanical work

flagella

long, hairlike projections from the cell surface that move cells

flagellin

makes up bacterial flagella and rotates like a propeller

microtubules

eukaryotic flagella are made of _________ and wave back and forth

one or two flagella, but may have many cilia

cells generally just have...

cilia

short, filament-like projections

"9 + 2"

a complex arrangement of microtubules connected by links and spokes in the axoneme of cilia and flagella

motor protein dynein

forms the arms between doublets and changes shape when ATP is hydrolyzed to "walk" up the microtubule

the links and bridges constrain movement of the microtubule doublets

when the dynein arms on just one side of the axoneme move, cilia and flagella BEND instead of elongating because.....

10 million ATP molecules per second

a typical cell uses, and synthesizes, appox....

25,000 reactions per second

a cellular enzyme can catalyze

the breadth of its organelle or cell in under a minute

each membrane phospholipid can travel.....

every 10 days, for as long as you live

the hundreds of trillions of mitochondria inside you are replaced about....

constantly changing

the fluid plasma membrane's composition is...

converts ATP into mechanical energy in the form of movement

what does a motor protein do in a cell?

NOT a component of the cytoskeleton

cilia

generates movement by the flagellum

microtubules

protective layer

wall that forms just beyond the cell membrane, usually consists of a "fiber composite"

fiber composite

a cross-linked network of long filaments surrounded by a stiff ground substance

function of extracellular layer

-The rods or filaments protect against tension

-The ground substance protects against compression

extracellular matrix

fiber composite in most animal cells

structural support

one of the extracellular matrix's most import functions

vary depending on the cell type

the amount and composition of the ECM...

collagen

the most common ECM protein, more elastic than cellulose and forms a flexible extracellular layer

integrin proteins

• helps attach cells to the ECM

• bind to adaptor proteins which link to actin filaments

• become activated by binding to molecules inside or outside the cell