Of Nuclei and Cells - Brian · PDF fileOf Nuclei and Cells ... Photoautotrophs and chemoautotrophs ... What is the difference between a prokaryote and a eukaryote?

Cells

Cell Structure and Function 1

Topic 5

Of Nuclei and Cells

CEB Textbook Chapter 4, pages

54-67

Mastering Biology, Chapter 4

Learning Objective

After studying this topic you should be able to:

Understand and use the metric system.

Recognise (in drawings or micrographs) and name

the main characteristics that differentiate prokaryotic

and eukaryotic cells.

Recognise (in drawings or micrographs), describe,

and understand the structure and function of the

following organelles: Nucleus, Ribosomes, and all

the components of the Endomembrane System.

Artists are often inspired

by biology and biology

depends on art

The paintings of Wassily

Kandinsky (1866-1944)

show the influence of

cellular forms

The Art of Looking at Cells Illustration is an important

way to represent what

scientists see through

microscopes

The anatomist Santiago

Ramón y Cajal (1852-

1934) was trained as an

artist

He drew these retina nerve

cells

The microscope was invented in the 17th century

Using a microscope, Robert Hooke discovered

cells in 1665

All living things are made of cells (cell theory)

INTRODUCTION TO THE WORLD

OF THE CELL The light microscope enables us to see the overall

shape and structure of a cell

4.1 Microscopes provide windows to the

world of the cell

Figure 4.1A

Image seen by viewer

Eyepiece

Ocular

lens

Objective lens

Specimen

Condenser lens

Light source

Cells


Electron microscopes were invented in the 1950s

They use a beam of electrons instead of light

The greater resolving power of electron

microscopes

allows greater magnification

reveals cellular details

Scanning

electron

microscope

(SEM)

Figure 4.1B

Scanning

electron

micrograph of

cilia

Transmission

electron

microscope

(TEM)

Figure 4.1C

Transmission

electron

micrograph of

cilia

Below is a list of the most common units of

length biologists use (metric)

4.2 Cell sizes vary with their function

Table 4.2

Cell size and

shape relate

to function

Figure 4.2

At minimum, a cell must be large enough to house

the parts it needs to survive and reproduce

The maximum size of a cell is limited by the

amount of surface needed to obtain nutrients from

the environment and dispose of wastes

4.3 Natural laws limit cell size

Cells


A small cell has a greater ratio of surface area to

volume than a large cell of the same shape

30 µm 10 µm

Surface area

of one large cube

= 5,400 µm2

Total surface area

of 27 small cubes

= 16,200 µm2 Figure 4.3

Types of Living Things

NON CELLULAR - Viruses

PROKARYOTIC – Lacks distinct nucleus (Bacteria)

EUKARYOTIC – Has distinct nucleus (include plant,

animal, fungi and protist cells)

PROKARYOTIC

CELLS (BACTERIA)

Prokaryotic cells are small, relatively simple cells

They lack nuclei and other membrane-

enclosed organelles

Prokaryotic cells are small and

structurally simple

Prokaryotes are the

oldest life-forms

They remain the most

numerous and

widespread organisms

on Earth today

Prokaryotes have inhabited Earth for

billions of years

PROKARYOTES

Figure 16.7

Prokaryotes are

classified into two

domains, based

on nucleotide

sequences and

other features

Bacteria and

Archaea

Table 16.8

Cells


Spheres (cocci) are

the most common

Rods (bacilli)

Prokaryotes come in a variety of shapes

Figure 16.9A-C

Curves or spirals

These E. Coli colonies are growing with only

glucose as an organic nutrient

Prokaryotes obtain nourishment in a variety of

ways

Figure 16.10

Autotrophs obtain carbon from CO2 and are of

two types

Photoautotrophs and chemoautotrophs

Heterotrophs obtain carbon from organic

compounds

Photo-

heterotrophs

and

chemo-

heterotrophs

Table 16.10

The first cells were most likely chemoautotrophs

They may have gotten their energy from sulfur and iron

compounds

Archaea live in

anaerobic swamps

salt lakes

acidic hot springs

deep-sea hydrothermal

vents

animal digestive systems

Archaea thrive in extreme environments—

and in the ocean

Figure 16.11A, B

Rotating flagella aid in

locomotion

Diverse structural features help prokaryotes

thrive almost everywhere

Figure 16.12A

Flagellum

Plasma membrane

Cell wall

Rotary movements of each flagellum

Cells


A prokaryotic cell is enclosed by a plasma

membrane and is usually encased in a rigid cell

wall

The cell wall may

be covered by a

sticky capsule Ribosomes

Figure 4.4

Capsule

Cell wall

Plasma

membrane

Prokaryotic

flagella

Nucleoid region

(DNA)

Pili

Inside the cell are

its DNA and

other parts

Pili help cells cling to surfaces

Figure 16.12B

Pili

Endospores allow certain bacteria to survive

environmental extremes in a resting stage

Figure 16.12C

Endospore

Many prokaryotes grow in linear filaments

Figure 16.12D

EUKARYOTIC

CELLS There are 4 main types

Fungi

Protists

Animals

Plants

All other life forms are made up of one or more

eukaryotic cells

These are larger and more complex than

prokaryotic cells

Eukaryotes are distinguished by the presence of

a true nucleus (surrounded by a membrane)

Eukaryotes, unlike prokaryotes, also have

membrane-enclosed structures called

organelles

4.5 Eukaryotic cells are partitioned

into functional compartments

Cells


Eukarya

Plants

Animals Fungi

Protists

2.7 billion years ago

Eukaryotes

FUNGI

FUNGI

Rarely discrete cells.

Nucleus and organelles are membrane bound.

Plant like but no chlorophyll.

Rigid cell walls that have chitin.

Heterotrophic.

Fungi

(yeasts, moulds and

mushrooms)

morels The Michigan fungus is estimated to be 1500 years old. It covers about 38 acres and weighs about 11,000 kg.

Number of fungal species: about 65,000.

UNICELLULAR

EUKARYOTES (PROTISTS) Protists (Unicellular Eukaryotes) –

Are single celled eukaryotes e.g. Paramecium

Found almost anywhere there is water

Discrete single cells or single cells in colonies

Nucleus and organelles are membrane bound.

Some are autotrophic and carry out photosynthesis.

Others heterotrophic (ingest food) – like animals.

Cells


Protists

Tetrahymena

SEM thanks to Stanley L. Erlandsen, and Dennis E. Feely, authors of "Trophozoite Motility and the Mechanism of Attachment," in Giardia and Giardiasis, Plenum Press, 1984

Giardia

Giardia lacks mitochondia, but contains two nuclei.

Amoeba

Amoeba

Anal Pore

Amoeba eats Paramecium - http://www.youtube.com/watch?v=pvOz4V699gk

They include

Unicellular dinoflagellates

Photosynthetic protists are called algae

Figure 16.23A

Flagellar groove

Flagellum

Diatoms

Green algae

Figure 16.23 B, C

These protists are

multicellular photosynthetic

organisms that lack the

structural specializations of

plants

Examples include

Brown algae

Red algae

Green algae

Seaweeds are multicellular marine algae

Figure 16.24A, B

http://www.youtube.com/watch?v=pvOz4V699gk




Cells


Brown algae seem closely related to diatoms

These groups may eventually be classified with

some other groups of protists in a separate

kingdom

Many biologists favor classifying red algae in

their own kingdom

Macronucleus

These slime molds have

unicellular stages

They also have stages

where they exist as

plasmodia, multinuclear

masses of cytoplasm

undivided by

membranes

Plasmodial slime molds form brightly

colored “supercells” with many nuclei

Figure 16.22A, B

Is Slime Mould Intelligent? -

http://www.youtube.com/watch?v=eXeygGxu8-8

Multicellularity evolved independently many times

Probably by specialization of the cells of colonial

protists

Multicellular life may have evolved from

colonial protists

Figure 16.25

Unicellular protist

1

Colony

2

Early multicellular organism with specialized, interdependent cells

Locomotor cells

Food- synthesizing cells

Somatic cells

3

Later organism that produces gametes

Gamete

Multicellular life

first arose over a

billion years ago

All life was

aquatic until

almost 500

million years ago

Multicellular life has diversified over

hundreds of millions of years

Figure 16.26

Multicellular organisms colonize land

Diverse multicellular algae, fungi, and animals, all living in the sea

Mass extinctions

Earliest animals; many multicellular algae

Oldest known fossils of multicellular eukaryotes (small algae)

Earliest multicellular eukaryotes?

Ag

e o

f fo

ssils i

n m

illio

ns o

f years

PR

EC

AM

BR

IAN

ER

A

PA

LE

OZ

OIC

E

RA

VIDEOS

Diversity of Protists (20 mins)

http://www.youtube.com/watch?v=Ln69k7LyTsU

ANIMAL CELLS












Cells


ANIMAL CELLS

Exist as part of multicellular organisms.

Nucleus and organelles membrane bound.

Lack cell walls (because we have skeletons).

Heterotrophic (take in nutrients from

outside/ingest food).

An animal cell

Plasma membrane

Figure 4.5A

Golgi

apparatus

Ribosomes

Nucleus Smooth

endoplasmic

reticulum Rough

endoplasmic

reticulum

Mitochondrion

Not in most

plant cells

Cytoskeleton

Flagellum

Lysosome

Centriole

Peroxisome

Microtubule

Intermediate

filament

Microfilament

The plasma membrane controls the cell’s contact

with the environment

The cytoplasm contains organelles

Many organelles have membranes as boundaries

These compartmentalize the interior of the cell

This allows the cell to carry out a variety of activities

simultaneously

Eukaryotes

REMEMBER - Cells are 3 dimensional !!

PLANT

CELLS

Cells


Plant cells

Exist as part of multicellular organisms.

Nucleus and organelles membrane bound.

Have cell walls (instead of skeleton).

Autotrophic = make their own food from raw

materials. ie. Photosynthesis (using chloroplasts)

Figure 4.5B

Nucleus

Golgi

apparatus

Not in

animal

cells

Central

vacuole

Chloroplast

Cell wall

Mitochondrion

Peroxisome

Plasma membrane

Rough

endoplasmic

reticulum Ribosomes

Smooth

endoplasmic

reticulum

Cytoskeleton

Microtubule

Intermediate

filament

Microfilament

A Plant Cell

A plant cell has some structures that an animal cell

lacks:

Chloroplasts – Captures sunlight for Photosynthesis

A rigid cell wall – Provides structure (because plants

don’t have skeletons)

A large vacuole

Summary Questions

What is the difference between a prokaryote and a

eukaryote?

What are the 4 main types of eukaryotic cells?

What is a protist?

How are plant cells and animal cells different and why?

Homework

Mastering Biology activity: Comparing

Prokaryotic and Eukaryotic Cells

Complete Bioflix study sheet: Tour of an Animal

Cell, Tour of a Plant Cell and comparing Animal

and Plant Cells

Complete Topic 5 in Unit Assessment 1

Animal and Plant Cells -

Organelles

Cells


Learning Objectives

• Describe the structure of a generalised animal

and plant cell and describe the functions of

cellular components and organelles

• Identify the similarities and differences between

plant and animal cells

Eukaryotes

Imagine the cell as factory that

creates a product It is usually the largest organelle

It is separated from the cytoplasm by the nuclear

envelope

It contains the DNA that directs the cell’s activities

The nucleus is the cell’s genetic control

center (Designer!)

ORGANELLES OF THE

ENDOMEMBRANE SYSTEM

Figure 4.6

Chromatin

Nucleolus

Pore

NUCLEUS

Two membranes

of nuclear

envelope

ROUGH

ENDOPLASMIC

RETICULUM

Ribosomes

The Nucleus

-Composed of two

concentric membranes

that form the nuclear

envelope.

-Contains a nucleolus

Cells


The Nucleolus Ribosomes (which become part of the rough endoplasmic reticulum) are produced in the nucleolus. This is where ribosomal RNA is transcribed.

Membranes are selectively permeable

They control the flow of substances into and out of a cell

Membranes organize the chemical

activities of cells (Manager!)

Cytoplasm

(inside cell)

Figure 5.10

Outside cell

The plasma membrane of an animal cell

Fibers of the

extracellular

matrix

Figure 5.12

Glycoprotein Carbohydrate

(of

glycoprotein)

Microfilaments

of the

cytoskeleton

Phospholipid

Cholesterol

Proteins

CYTOPLASM

(inside)

Glycolipid

Nuclear Pores

The nuclear envelope

has pores and is

continuous with the

Endoplasmic

Reticulum (ER)

Nuclear pores allow RNA and protein to move in and out of the nucleus.

Endoplasmic Reticulum

(ER)(Manufacturing!)

Cell membrane components and materials to be

exported from the cell are made here

Proteins are synthesised on Rough ER

Lipids (Fats) are produced on Smooth ER. In

some cells, Smooth ER regulates carbohydrate

metabolism and breaks down toxins and drugs

SMOOTH ER

ROUGH

ER

Nuclear

envelope

Ribosomes

SMOOTH ER ROUGH ER

Figure 4.9

Cells


The rough ER manufactures membranes

Ribosomes (the rough part) on its surface produce proteins

The Rough Endoplasmic Reticulum

(Manufacturer) makes membrane and

proteins

1 2

3

4 Transport vesicle

buds off

Ribosome

Sugar

chain

Glycoprotein

Secretory

(glyco-) protein

inside transport

vesicle

ROUGH ER

Polypeptide Figure 4.8

Rough Endoplasmic Reticulum (ER)

The Golgi Apparatus (Shipping out!)

The Golgi apparatus consists of stacks of

membranous sacs

The Golgi apparatus finishes, sorts, and ships cell

products

These receive and modify ER products, then send

them on to other organelles or to the outer cell

membrane

ANY CELL that secretes substances has lots of

these! (e.g. glands in the pancreas and intestinal wall,

salivary glands)

The Golgi apparatus

Golgi

apparatus

“Receiving” side of

Golgi apparatus

Transport

vesicle

from ER

New

vesicle

forming

Transport vesicle

from the Golgi

Golgi apparatus

“Shipping”

side of Golgi

apparatus Figure 4.10

Golgi Apparatus

Mitochondria (Power supply!) are the

energy factories of the cell Two membranes, the

inner one folded to

increase surface area.

Maternally inherited

Contain their own DNA

and replicate (possibly

because they were once

separate unicellular

organisms)

REMEMBER Cells which have high energy requirements have

lots of these. E.g. Muscle cells, sperm and cells that do

active transport.

Cells


Lysosomes are sacs

of digestive

enzymes budded off

the Golgi

They digest the

cell’s food and

wastes

Lysosomes (Cleaners!)

LYSOSOME

Nucleus

Figure 4.11A

Lysosomal Enzymes

digest food

destroy bacteria

recycle damaged

organelles

function in embryonic

development in animals

Figure 4.11B

Rough ER

Transport vesicle

(containing inactive

hydrolytic enzymes)

Golgi

apparatus

Plasma

membrane

LYSOSOMES

“Food”

Engulfment

of particle

Food

vacuole

Digestion

Lysosome

engulfing

damaged

organelle

Lysosomal storage diseases are hereditary

They interfere with other cellular functions

Examples: Pompe’s disease, Tay-Sachs disease

Connection: Abnormal lysosomes can cause fatal

diseases

Plant cells A plant cell has some extra structures that an

animal cell lacks:

Chloroplasts – Captures sunlight for Photosynthesis

A rigid cell wall – Provides structure (because plants

don’t have skeletons)

A large vacuole

Cells


Chloroplasts Chloroplasts (Plant cells only)

Composed of internal folded membranes

where the chemical reactions in

photosynthesis takes place.

Using energy from sunlight to convert carbon

dioxide and water to sugar (photosynthesis)

Contain their own DNA and replicate by

dividing

Cell Wall (Plant cells only)

Plant cells are supported by rigid cell walls made

largely of cellulose

These provide support (instead of a skeleton)

They connect by plasmodesmata, channels that

allow them to share water, food, and chemical

messages

Figure 4.19A

Vacuole

Layers of one

plant cell wall

Walls of two

adjacent

plant cells

PLASMODESMATA

Cytoplasm

Plasma membrane

Plant cells contain a

large central

vacuole

Vacuoles function

in the general

maintenance of the

cell

The vacuole has

lysosomal and

storage functions

Vacuoles

Central

vacuole

Nucleus

Figure 4.13A

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

Cells interact with their environments and each other via their surfaces (membranes)

A review of the endomembrane system

Transport vesicle from ER

Rough ER

Transport vesicle from Golgi

Plasma membrane

Vacuole

Lysosome

Golgi apparatus Nuclear

envelope

Smooth ER

Nucleus

Figure 4.14

Cells


SUMMARY - Eukaryotic organelles fall into four functional groups

Eukaryotic organelles comprise four

functional categories

Table 4.20 Table 4.20 (continued)

Summary Questions

What are the three main differences between a

plant and an animal cell?

Homework

Mastering Biology activity: Comparing

Prokaryotic and Eukaryotic Cells

Complete Bioflix study sheet: Tour of an Animal

Cell, Tour of a Plant Cell and comparing Animal

and Plant Cells (pge 26-30 study notes)

Complete Topic 5 on Unit Assessment 1

Documents

Of Nuclei and Cells - Brian · PDF fileOf Nuclei and Cells ... Photoautotrophs and chemoautotrophs ... What is the difference between a prokaryote and a eukaryote?