Unit A: CellsCh. 4

A Tour of the Cell

Standards

By the end of this unit you should be able to:

Recognize and explain the function of each organelle

Look at micrographs/diagrams/pictures and correctly ID each organelle

Write/work with/explain the balanced chemical equation for cellular respiration

Relate the role of an organelle to a specific part of the body

Explain how the endomembrane system functions to compartmentalize the cell and move materials through it

Cell Intro

Big Picture – in case you did not know!!!

Life = Cells

Cells=prokaryotic

(bacteria) OR

eukaryotic (all other)

How do you recognize????

Cells EVERYWHERE!!!

Apoptosis in a Leukemia

Cell – Cell Suicide

Staphylococcus

aureus

Human Red Blood

Cells

Escherichia coli

Cells Everywhere!!!

How big is a cell????

How many cells in your body???

50 million million (50 trillion) cells – stretched end to end they would stretch around the Earth 47 times – if you could count one cell per second it would take you 2600 years !!!

Inner Life of Cell

What cells can you see???

Hummingbird Egg

– 0.02 ounces Beluga sturgeon

Eggs - $700 per

ounce

Human Egg –

Thousands of

dollars per egg -

25G’s

Cells vary in size and shape

Most cells are microscopic

Human height

Length of some

nerve and

muscle cells

Chicken egg

Frog egg

Una

ide

d e

ye

Lig

ht m

icro

sco

pe

Ele

ctr

on

mic

rosco

pe

10 m

1 m

100 mm

(10 cm)

10 mm

(1 cm)

1 mm

100 m

10 m

1 m

100 nm

10 nm

1 nm

0.1 nmAtoms

Proteins

Small molecules

Lipids

Viruses

Ribosome

Nucleus

Mycoplasmas

(smallest bacteria)

Most plant and

animal cells

Most bacteria

Mitochondrion

Figure 4.2A

What

cells can

you

see???

30 m10 m

30 m 10 m

Surface area

of one large cube

5,400 m2

Total surface area

of 27 small cubes

16,200 m2Figure 4.2B

The microscopic size of most cells ensures a sufficient sur face area

Across which nutrients and wastes can move to service the cell volume

A small cell has a greater ratio of sur face area to volume than a large cell of the same shapeSurface

area to

volume

ratio

Recall: there are two kinds of cells

Prokaryotic and eukaryotic, which is which and how do you know?

Prokaryotic cell

Nucleoid

region

Nucleus

Eukaryotic cell Organelles

Colo

rize

d T

EM

15

,00

0

Figure 4.3A

4.3 Prokaryotic

cells are

structurally

simpler than

eukaryotic cells

A.

B.

Prokaryotic

flagella

Ribosomes

Capsule

Cell wall

Plasma

membrane

Nucleoid region (DNA)

Pili

Prokaryotic cells are small, relatively simple cells

That do not have a membrane-bound nucleus

You should recall all the “bits” from Gr 11 microbiology (bacteria)

Figure 4.3B

Prokaryotic

Cells

4.4 Eukaryotic cells are partitioned into functional compartments (organelles)

All other forms of life (anything not bacteria) are composed of more complex eukaryotic cells

Distinguished by the presence of a true nucleus

Membranes form the boundaries of and within many eukaryotic cells

Compartmentalizing the interior of the cell into organelles and facilitating a variety of metabolic activities

Eukaryotic

Cells

There are two types of Eukaryotic cells: animal and plant

A typical animal cell contains a variety of membranous organelles

NucleusSmooth endoplasmic

reticulumRough

endoplasmic

reticulum

Ribosomes

Golgi

apparatus

Plasma membrane

Mitochondrion

Flagellum

Not in most

plant cells Lysosome

Centriole

Microtubule

CytoskeletonIntermediate

filament

Microfilament

Peroxisome

Figure 4.4A

Types of

Eukaryotic

Cells

A typical plant cell has some structures that an animal cell lacks

Such as chloroplasts, a rigid cell wall and a central vacuole

Central

vacuoleNot in

animal

cellsChloroplast

Cell wall

Golgi

apparatus

Nucleus

Microtubule

CytoskeletonIntermediate

filament

Microfilament

Ribosomes

Smooth

endoplasmic

reticulum

Mitochondrion

Peroxisome

Plasma membrane

Rough

endoplasmic

reticulum

Figure 4.4B

Types of

Eukaryotic

Cells

Plant and Animal Differences:The 4 C’s!

Plant CellCell wall

Chloroplasts

Central Vacuole

Animal Cell Centrioles

Cytoplasm

All other organelles found here

Defined by cell membrane & envelope

Cytoskeleton – maintains cell’s shape

The nucleus is the cell’s genetic control center

Its the largest organelle which is separated from the cytoplasm by the nuclear envelope

The nucleus is the cellular control center

It contains the cell’s DNA, which directs cellular activities

NucleusChromatin

Nucleolus

Pore

Ribosomes

Rough

endoplasmic

reticulum

Two membranes

of nuclear

envelope

Figure 4.5

4.5 The

Nucleus

NuclearStructure

i) Nuclear Envelope – 2 membranes with pores

ii) Chromatin – thread likeBecomes chromosomes* (condensed) during cell division*Contains genetic material (DNA):

Meaningful parts = genesMade of - DNA & proteins

iii) Nucleolus – dark centerMakes rRNA (ribosomal RNA)

Many cell organelles are connected through the endomembrane system

a collection of membranous organelles that manufactures and distributes cell products

Nucleus, RER, SER, Golgi, Vesicles, Vacuoles

4.6

Endomembrane

System

Smooth endoplasmic reticulum (SER) has a variety of functions

Synthesizes lipids

Processes toxins and drugs in liver cells

Stores and releases calcium ions in muscle cells

Smooth ER

Rough ER

Nuclear

envelope

Rough ER

Ribosomes

Smooth ER

TE

M 4

5,0

00

Figure 4.7

4.7

SER

Rough endoplasmic reticulum (RER) makes membrane and proteins

Ribosomes on the surface of the RER

Produce proteins that are secreted, inserted into RER membranes, or transported in vesicles to other organelles

4 stages of protein synthesis???

4.8:

RER

And

Ribosomes

Figure 4.8

ER Comparison

RER

Studded with ribosomes

Synthesize proteins for export (use outside of the cell)

Ex - insulin

SER

NO ribosomes

Synthesize lipids

(ex. Male testes – make testosterone – a lipid steroid – so lots of SER)

Help liver in detox. process

ER – interconnected membrane, tubular canals,

begin at nuclear envelope

2 Types of Ribosomes

Free Floating

Make proteins for cell use (internal)

Embedded in RER

Make proteins for export out of cell (external)

The Golgi apparatus finishes, sorts, and ships cell products

Stacks of membranous sacs receive and modify ER products then ships them to other organelles or the cell surface

Figure 4.9

Golgi apparatus

TE

M 1

30

,000

Transport

vesicle from

the Golgi“Shipping” side

of Golgi apparatus

Golgi

apparatus

“Receiving” side of

Golgi apparatus

Transport

vesicle

from ER

New vesicle

forming

4.9 Golgi

Apparatus

Lysosomes are digestive compartments within a cell Sacs of hydrolytic enzymes that function in hydrolysis

(digestion) within a cell

Double membrane bound and made by GA

Function in autodigestion EX: tadpole tail, finger webbing

Figure 4.10A

Golgi

apparatus

Plasma

membrane

“Food”

Food

vacuole

Lysosomes

2

Lysosome

engulfing

damaged

organelle

5

Digestion4

3

Engulfment

of particle

Transport vesicle

(containing inactive

hydrolytic enzymes)

1

Rough ER

4.10

Lysosomes

lysosomes clip

Lysosomes in white blood cells Destroy bacteria that have been ingested

Lysosomes also recycle damaged organelles

Abnormal lysosomes can cause fatal diseases (Lysosomal storage diseases) which interfere with various cellular functions

Figure 4.10B

Lysosome

Nucleus

TE

M 8

,50

0

4.10

Lysosomes

TE

M 4

2,5

00

Lysosome containing

two damaged organelles

Mitochondrion fragment

Peroxisome fragment

Figure 4.10C

Vacuoles function in the general maintenance of the cell

Plant cells contain a large central vacuole which has lysosomal and storage functions as well as support functions

Some protists have contractile vacuoles that pump out excess water

Chloroplast

Central

vacuole

NucleusC

olo

rized T

EM

8,7

00

Figure 4.12A

4.12

Vacuoles

LM

65

0

Nucleus

Contractile

vacuolesFigure 4.12B

The various organelles of the endomembrane system are interconnected structurally and functionally

Nucleus

Smooth ER Nuclear envelope Golgi apparatus

Lysosome

Vacuole

Plasma

membrane

Rough ER

Transport vesicle

from ER to Golgi

Transport vesicle from

Golgi to plasma membrane

Figure 4.13

A review of the

endomembrane

system

ENERGY-CONVERTING ORGANELLES

4.14 Chloroplasts convert solar energy to chemical energy

Chloroplasts, found in plants and some protists, convert solar energy to chemical energy in sugars (glucose)

Contains chlorophyll

TE

M 9

,750

Chloroplast

Stroma

Intermembrane

space

Inner and outer

membranes

Granum

Figure 4.14

4.15 Mitochondria harvest chemical energy from food

Mitochondria carry out cellular respiration which uses the chemical energy in food (glucose) to make ATP for cellular work

OXYGEN + GLUCOSE ---- CARBON DIOXIDE + ATP + WATER

Double membrane bound, has own DNA

Figure 4.15

Mitochondrion

Outer

membrane

Intermembrane

space

Matrix

Inner

membrane

Cristae

TE

M 4

4,8

80

ENERGY-

CONVERTING

ORGANELLES

The cell’s internal skeleton helps organize its structure and activities

A network of protein fibers make up the cytoskeleton.

Microfilaments of actin Enable cells to change shape and move

Intermediate filaments Reinforce the cell and anchor certain organelles

Microtubules give the cell rigidity And provide anchors for organelles and act as

tracks for organelle movement

Actin subunit

Microfilament

7 nm

Fibrous subunits

10 nm

Intermediate filament Microtubule

25 nm

Tubulin subunit

Figure 4.16

4.16

Cytoskeleton

Cilia and flagella move when microtubules bend

Eukaryotic cilia and flagella are locomotor appendages that protrude from certain cells

Clusters of microtubules drive the whipping action of these organelles

LM

60

0

Colo

rize

d S

EM

4,1

00

Figure 4.17A Figure 4.17B

4.17

Cilia and

FlagellaFlagellum Electron micrographs

of cross sections:

Flagellum

Basal body

Basal body

(structurally identical to

centriole)

TE

M 2

06,5

00

TE

M 2

06,5

00

Plasma

membrane

Dynein arms

Radial spoke

Central

microtubules

Outer microtubule

doublet

Figure 4.17C

4.19 CELL SURFACES AND JUNCTIONS

Cell surfaces protect, support, and join cells Cells interact with their environments and each other via their

surfaces.

Plant cells

Are supported by rigid cell walls made largely of cellulose

Connect by plasmodesmata, which are connecting channels

Plasma membrane

Cytoplasm

Plasmodesmata

Vacuole

Layers of one

plant cell wall

Walls of two

adjacent plant

cells

Figure 4.18A

Animal cells Animal cells are embedded in an extracellular

matrix which binds cells together in tissues

Tight junctions can bind cells together into leak-proof sheets

Anchoring junctions link animal cells into strong tissues

Gap junctions allow substances to flow from cell to cell

4.19 CELL SURFACES AND JUNCTIONS

Anchoring junction

Tight junctions

Gap junctions

Extracellular matrix

Space between cells

Plasma membranes of adjacent cells

Figure 4.18B

FUNCTIONAL CATEGORIES OF ORGANELLES 4.19 Eukaryotic organelles comprise four functional categories

Eukar yotic organelles fall into four functional groups

Manufacturing

Breakdown

Energy processing

Suppor t, movement, and communication between cells

Table 4.19