CHAPTER 3: CELLS - classpages.warnerpacific.edu - /classpages.warnerpacific.edu/bdupriest/BIO 221/Chapter 3...Copyright © 2010 Pearson Education, Inc. CHAPTER 3: CELLS Copyright ©

Copyright © 2010 Pearson Education, Inc.

CHAPTER 3: CELLS


CELL THEORY


CELL DIVERSITY


Figure 3.1 Cell diversity.

Fibroblasts

Erythrocytes

Epithelial cells

(d) Cell that

fights disease

Nerve cell

Fat cell

Sperm

(a) Cells that connect body parts,

form linings, or transport gases

(c) Cell that stores

nutrients

(b) Cells that move organs and

body parts

(e) Cell that gathers information

and control body functions

(f) Cell of reproduction

Skeletal

Muscle

cell

Smooth muscle cells

Macrophage


The concept that a cell has a unique shape

which allows it to perform a unique function

is an example of…

1) Homeostasis

2) Complementarity of structure

and function

3) Negative feedback


The smallest unit which has all the properties

of life is…

1) a cell

2) a tissue

3) an organism

4) a protein


GENERALIZED CELL


Figure 3.2 Structure of the generalized cell.

Nucleus

Organelles Cytoskeleton

Cytosol

Cytoplasm

Plasma

membrane


PLASMA MEMBRANE STRUCTURE


Figure 3.3 Structure of the plasma membrane according to the fluid mosaic model.

Integral

proteins

Extracellular fluid

(watery environment)

Cytoplasm

(watery environment)

Polar head of

phospholipid

molecule Glycolipid

Cholesterol

Peripheral

proteins Bimolecular

lipid layer

containing

proteins

Inward-facing

layer of

phospholipids

Outward-

facing

layer of

phospholipids

Carbohydrate

of glycocalyx

Glycoprotein

Filament of cytoskeleton

Nonpolar tail of phospholipid molecule


Figure 3.4a Membrane proteins perform many tasks.

(a) Transport

Signal

Receptor

(b) Receptors for signal transduction


Figure 3.4c Membrane proteins perform many tasks.

(c) Attachment to the

cytoskeleton and

extracellular matrix (ECM)

Enzymes

(d) Enzymatic activity


Figure 3.4e Membrane proteins perform many tasks.

CAMs

(e) Intercellular joining

Glycoprotein

(f) Cell-cell recognition


EXTRACELLULAR JUNCTIONS


Figure 3.5 Cell junctions.

Interlocking

junctional

proteins

Intercellular

space

Intercellular

space

Plasma membranes

of adjacent cells Microvilli

Intercellular

space

Basement membrane

Plaque

Linker

glycoproteins

(cadherins)

Intermediate

filament

(keratin)

Intercellular

space

Channel

between cells

(connexon)

(a) Tight junctions: Impermeable

junctions prevent molecules

from passing through the

intercellular space.

(b) Desmosomes: Anchoring

junctions bind adjacent cells

together and help form an

internal tension-reducing

network of fibers.

(c) Gap junctions: Communicating

junctions allow ions and small

molecules to pass from one cell

to the next for intercellular

communication.


Phospholipids interact with the intracellular

fluid and extracellular fluid via their…

1) Glycerol

2) Polar head group

3) Hydrophobic tails

4) Cholesterol

5) Proteins


The “hydrophobic core” of the membrane is

formed by which of the following?

1) Glycerol in triglycerides

2) Polar head groups in phospholipids

3) Nonpolar tails in phospholipids

4) Cholesterol

5) Proteins

6) Carbohydrates

7) RNA


Integral proteins (embedded in the membrane)

can have all EXCEPT which of these functions?

1) Joining adjacent cells together

2) Catalyzing reactions

3) Making new proteins

4) Transporting ions into the cell

5) Anchoring the cell in place


PLASMA MEMBRANE TRANSPORT


PASSIVE TRANSPORT:

DIFFUSION & OSMOSIS


Figure 3.6 Diffusion.


Figure 3.7 Diffusion through the plasma membrane.

Extracellular fluid

Lipid-

soluble

solutes

Cytoplasm

Lipid-insoluble

solutes (such as

sugars or amino

acids)

Small lipid-

insoluble

solutes

Water

molecules

Lipid

billayer

Aquaporin

(a) Simple diffusion of

fat-soluble molecules

directly through the

phospholipid bilayer

(b) Carrier-mediated facilitated

diffusion via a protein carrier

specific for one chemical; binding of

substrate causes shape change in

transport protein

(c) Channel-mediated

facilitated diffusion through a channel protein; mostly ions selected on basis of size and charge

(d) Osmosis, diffusion

of a solvent such as

water through a

specific channel protein

(aquaporin) or through

the lipid bilayer


(a) Membrane permeable to both solutes and water

Solute and water molecules move down their concentration gradients

in opposite directions. Fluid volume remains the same in both compartments.

Left compartment: Solution with lower osmolarity

Right compartment: Solution with greater osmolarity

Membrane

H2O

Solute

Solute molecules (sugar)

Both solutions have the same osmolarity: volume unchanged

Figure 3.8a Influence of membrane permeability on diffusion and osmosis.


(b) Membrane permeable to water, impermeable to solutes

Both solutions have identical osmolarity, but volume of the solution on the right is greater because only water is free to move

Solute molecules are prevented from moving but water moves by osmosis.

Volume increases in the compartment with the higher osmolarity.

Left compartment

Right compartment

Membrane

Solute molecules (sugar)

H2O

Figure 3.8b Influence of membrane permeability on diffusion and osmosis.


Figure 3.9 The effect of solutions of varying tonicities on living red blood cells.

Cells retain their normal size and

shape in isotonic solutions (same solute/water concentration as inside

cells; water moves in and out).

Cells lose water by osmosis and

shrink in a hypertonic solution

(contains a higher concentration

of solutes than are present inside

the cells).

(a) Isotonic solutions (b) Hypertonic solutions (c) Hypotonic solutions

Cells take on water by osmosis until

they become bloated and burst (lyse) in a hypotonic solution (contains a

lower concentration of solutes than are present in cells).


ACTIVE TRANSPORT:

PUMPS


Figure 3.10 Primary Active Transport: The Na+-K+ Pump

Extracellular fluid

6 K+ is released from the pump protein

and Na+ sites are ready to bind Na+ again.

The cycle repeats.

2 Binding of Na+ promotes

phosphorylation of the protein by ATP.

1 Cytoplasmic Na+ binds to pump protein.

Na+

K+ released

ATP-binding site Na+ bound

Cytoplasm

ATP ADP

P

K+

5 K+ binding triggers release of the

phosphate. Pump protein returns to its

original conformation.

3 Phosphorylation causes the protein to

change shape, expelling Na+ to the outside.

4 Extracellular K+ binds to pump protein.

Na+ released

P

K+

P

Pi

Na+–K+ pump

K+ bound

McGraw-Hill Animation

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html




Figure 3.11 Secondary active transport.

1 2 The ATP-driven Na+-K+ pump

stores energy by creating a

steep concentration gradient for

Na+ entry into the cell.

As Na+ diffuses back across the

membrane through a membrane

cotransporter protein, it drives glucose

against its concentration gradient

into the cell. (ECF = extracellular fluid)

Na+-glucose

symport

transporter

loading

glucose from

ECF

Na+-glucose

symport transporter

releasing glucose

into the cytoplasm

Glucose

Na+-K+

pump

Cytoplasm

Extracellular fluid


Which of the following is an active process?

1) Oxygen moving from blood into cells

2) Glucose moving into cells from plasma

3) Carbon dioxide moving from cells to blood

4) Moving sodium ions out of the cell


VESICULAR TRANSPORT


Figure 3.12 Events of endocytosis mediated by protein-coated pits.

Coated pit ingests

substance.

Protein-

coated

vesicle

detaches.

Coat proteins detach

and are recycled to

plasma membrane.

Uncoated vesicle fuses with a sorting vesicle called an endosome.

Transport vesicle containing

membrane components moves to the plasma

membrane for recycling.

Fused vesicle may (a) fuse with lysosome for digestion of its contents, or (b) deliver its contents to the plasma membrane on the opposite side of the cell (transcytosis).

Protein coat (typically clathrin)

Extracellular fluid Plasma

membrane

Endosome

Lysosome

Transport

vesicle

(b) (a)

Uncoated

endocytic vesicle

Cytoplasm

1

2

3

4

5

6


Phagosome

(a) Phagocytosis

Figure 3.13a Comparison of three types of endocytosis.

(b) Pinocytosis

(c) Receptor-mediated

endocytosis


Figure 3.14b Exocytosis.


Figure 3.14a Exocytosis.

1 The membrane- bound vesicle migrates to the plasma membrane.

2 There, proteins at the vesicle surface (v-SNAREs) bind with t-SNAREs (plasma membrane proteins).

(a) The process

of exocytosis Extracellular fluid

Plasma membrane SNARE (t-SNARE)

Secretory vesicle

Vesicle SNARE (v-SNARE)

Molecule to be secreted

Cytoplasm

Fused v- and

t-SNAREs

3 The vesicle and plasma membrane fuse and a pore opens up.

4 Vesicle contents are released to the cell exterior.

Fusion pore formed


Which of the following occurs when an immune

cell “eats” pieces of foreign material?

1) Receptor-mediated endocytosis

2) Phagocytosis

3) Endocytosis

4) Exocytosis


CYTOPLASM


Figure 3.2 Structure of the generalized cell.

Secretion being released from cell by exocytosis

Peroxisome

Ribosomes

Rough endoplasmic reticulum

Nucleus

Nuclear envelope Chromatin

Golgi apparatus

Nucleolus

Smooth endoplasmic reticulum

Cytosol

Lysosome

Mitochondrion

Centrioles

Centrosome matrix

Cytoskeletal elements • Microtubule • Intermediate filaments

Plasma membrane


ORGANELLES


Figure 3.17 Mitochondrion.

Enzymes

Matrix

Cristae

Mitochondrial DNA

Ribosome

Outer mitochondrial membrane

Inner mitochondrial membrane

(b)

(a)

(c)


Figure 3.18 The endoplasmic reticulum.

Nuclear

envelope

Ribosomes

Rough ER

Smooth ER

(a) Diagrammatic view of smooth

and rough ER (b) Electron micrograph of

smooth and rough ER

(10,000x)


Figure 3.19 Golgi apparatus.

Cis face— “receiving” side of Golgi apparatus

Secretory

vesicle

(a) Many vesicles in the process of pinching

off from the membranous Golgi apparatus.

(b) Electron micrograph of the Golgi

apparatus (90,000x)

Transport vesicle from the Golgi apparatus

Transport vesicle from trans face

Trans face— “shipping” side of Golgi apparatus

New vesicles forming

New vesicles forming

Cisternae

Transport vesicle from rough ER

Golgi apparatus


Figure 3.20 The sequence of events from protein synthesis on the rough ER to the final distribution of those proteins.

Protein- containing vesicles pinch off rough ER and migrate to fuse with membranes of Golgi apparatus.

Proteins are modified within the Golgi compartments.

Proteins are then packaged within different vesicle types, depending on their ultimate destination.

Plasma membrane

Secretion by exocytosis

Vesicle becomes lysosome

Golgi

apparatus

Rough ER ER membrane

Phagosome

Proteins in cisterna

Pathway B:

Vesicle membrane

to be incorporated into plasma

membrane Pathway A:

Vesicle contents destined for exocytosis Extracellular fluid

Secretory

vesicle

Pathway C:

Lysosome containing

acid hydrolase enzymes

1

3

2


Figure 3.21 Electron micrograph of a cell containing lysosomes (12,000x).

Lysosomes

Light areas are regions where

materials are being digested.


What is the function of the Golgi apparatus?

1) To make proteins

2) To convert glucose into ATP

3) To finish, package, and sort proteins

4) To fold proteins


CYTOSKELETON


Figure 3.23 Cytoskeletal elements support the cell and help to generate movement.

Strands made of spherical protein

subunits called actins

Tough, insoluble protein fibers

constructed like woven ropes

(a) Microfilaments (b) Intermediate filaments (c) Microtubules

Hollow tubes of spherical protein

subunits called tubulins

Actin subunit

7 nm 10 nm 25 nm

Fibrous subunits

Tubulin subunits

Microfilaments form the blue network surrounding the pink nucleus in this photo.

Intermediate filaments form the purple batlike network in this photo.

Microtubules appear as gold networks surrounding the cells’ pink nuclei in this photo.


Figure 3.24 Microtubules and microfilaments function in cell motility by interacting with motor molecules.

Cytoskeletal elements (microtubules or microfilaments)

Motor molecule (ATP powered)

ATP

(b) In some types of cell motility, motor molecules attached to one

element of the cytoskeleton can cause it to slide over another element, as in muscle contraction and cilia movement.

ATP

Vesicle

(a) Motor molecules can attach to receptors on

vesicles or organelles, and “walk” the organelles

along the microtubules of the cytoskeleton.

Motor molecule (ATP powered)

Microtubule of cytoskeleton

Receptor for motor molecule


Figure 3.25 Centrioles.

Centrosome matrix

(b)

(a)

Centrioles

Microtubules


CELLULAR EXTENSIONS


Figure 3.26 Structure of a cilium.

Plasma

membrane

Outer microtubule

doublet

Dynein arms

Central

microtubule

Radial spoke

Radial spoke

TEM

TEM

Triplet

Basal body

(centriole)

Cilium

Microtubules

Plasma

membrane

Basal body

Cross-linking

proteins inside

outer doublets

Cross-linking

proteins inside

outer doublets

A longitudinal section of a cilium shows microtubules running the length of the structure.

The doublets also have attached motor proteins, the dynein arms.

The outer microtubule doublets and the two central microtubules are held together by cross-linking proteins and radial spokes.

A cross section through the basal body. The nine outer doublets of a cilium extend into a basal body where each doublet joins another microtubule to form a ring of nine triplets.

A cross section through the cilium shows the “9 + 2” arrangement of microtubules.

TEM


Figure 3.28 Microvilli.

Microvillus

Actin

filaments

Terminal

web


Which of these is NOT a function

of microtubules?

1) To help cilia move

2) To help chromosomes move during mitosis

3) To help carry cargo around the cell

4) To make muscle cells contract


THE NUCLEUS


Figure 3.29 The nucleus.

Chromatin

(condensed)

Nuclear

envelope Nucleus

Nuclear pores

Fracture line

of outer

membrane

Nuclear pore

complexes. Each

pore is ringed by protein particles.

Surface of nuclear envelope.

Nuclear lamina.

The netlike lamina

composed of

intermediate

filaments formed

by lamins lines the

inner surface of the

nuclear envelope.

Nucleolus

Cisternae of

rough ER

(a)

(b)


Figure 3.30 Chromatin and chromosome structure.

Metaphase

chromosome

(at midpoint

of cell division)

Nucleosome (10-nm diameter; eight histone proteins wrapped by two winds of the DNA double helix)

Linker DNA

Histones

(a)

(b)

1 DNA double

helix (2-nm diameter)

2 Chromatin

(“beads on a

string”) structure

with nucleosomes

3 Tight helical fiber

(30-nm diameter)

5 Chromatid

(700-nm diameter)

4 Looped domain

structure (300-nm

diameter)


The “beads” on a string of chromatin, made

f DNA and histone proteins, are…

1) linkers

2) chromosomes

3) chromatids

4) nucleosomes


CELL GROWTH & REPRODUCTION


CELL CYCLE


Figure 3.31 The cell cycle.

G1

Growth

S

Growth and DNA

synthesis G2

Growth and final

preparations for

division M

G2 checkpoint

G1 checkpoint

(restriction point)


MITOSIS


Figure 3.33 Mitosis (1 of 2)

Centrosomes

(each has 2

centrioles)

Early

mitotic

spindle

Spindle pole

Kinetochore Kinetochore

microtubule

Polar microtubule

Nucleolus

Interphase Early Prophase Late Prophase

Centromere

Plasma

membrane Fragments

of nuclear

envelope Aster

Nuclear

envelope

Chromosome

consisting of two

sister chromatids

Chromatin

Interphase Early Prophase Late Prophase


Figure 3.33 Mitosis (2 of 2)

Contractile

ring at

cleavage

furrow

Nuclear

envelope

forming

Nucleolus forming

Spindle

Metaphase

plate

Metaphase Anaphase Telophase

Daughter

chromosomes

Metaphase Anaphase Telophase and

Cytokinesis


When DNA is folded into relatively loose, long

strands during interphase, this is called…

1) chromatin

2) chromosomes

3) centromeres

4) nucleosomes


Sister chromatids are separated into two

identical distinct chromosomes during…

1) anaphase

2) metaphase

3) prophase

4) telophase


PROTEIN SYNTHESIS:

THE CENTRAL DOGMA


Figure 3.34 Simplified scheme of information flow from the DNA gene to mRNA to protein structure during

transcription and translation.

Nuclear pores

mRNA

Pre-mRNA RNA Processing

Transcription

Translation

DNA

Nuclear envelope

Ribosome

Polypeptide


EXTRACELLULAR FLUID &

THE EXTRACELLULAR MATRIX


DEVELOPMENTAL ASPECTS OF CELLS


The fluid and proteins surrounding a cell are

called the …

1) Intracellular fluid

2) Extracellular fluid

3) Extracellular matrix

4) Intercellular matrix


A cell which retains the ability to divide over

and over throughout life is called a …

1) Stem cell

2) Mature cell

3) Differentiated cell

4) Embryonic cell

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CHAPTER 3: CELLS - classpages.warnerpacific.edu - /classpages.warnerpacific.edu/bdupriest/BIO 221/Chapter 3...Copyright © 2010 Pearson Education, Inc. CHAPTER 3: CELLS Copyright ©