BIOLOGY 1A03Cellular and Molecular Biology

1

Theme 1: The Structure of the Cell

Module 2: Organelles and Energy

• Recognize the evolution of organelles through endosymbiosis.

• Identify the benefits of compartmentalization.

• Describe the important roles played by chloroplasts and mitochondria.

• Explain why carbohydrates are the primary source of energy in our bodies.

Learning Objectives 2

3

Eukaryotes and Prokaryotes

Unit 1

3

4

The Precambrian (Hadean, Archaean, and Proterozoic Eons) included the origin of life,

photosynthesis, and the oxygen atmosphere.

Life and photosynthesis began ~4 billion years ago

4570 3800 2500 542

Millions of years ago (mya) All life is unicellular Multicellular organisms begin to diversify slowly

Form

ation of s

olar syst

em

Earth

form

ation co

mplete

Liquid w

ater o

n Earth

First

oceans f

orm

Origins o

f life

First

evidence

of photo

synth

etic c

ells

First

evidence

of oxy

genic

photosyn

thesis

First

rock

s contai

ning oxy

gen

First

eukaryo

tic fo

ssils

First

photosyn

theti

c euka

ryotes

First

red alga

e and ev

idence of s

exual

structu

res

First

lichen-lik

e organism

First

sponge

s, bila

terally

symmetr

ic an

imals

, oce

an

fully oxy

genate

d

5

Eukaryotic cells: an organism whose cells

contain a nucleus and many membrane-

bound organelles.

Structural differences: eukaryotic and prokaryotic cells

Prokaryotic cells: unicellular organisms that lack a nucleus and have few to no organelles.

Prokaryotes and eukaryotes share a common ancestor6

Common ancestor

Animals Fungi Plants Protists Archaea Bacteria

Eukaryotes Prokaryotes

0

2

4

Billi

on y

ears

ago

7

Organelles are membrane-bound

structures inside the cell.

• Chloroplasts in plant cells

• Mitochondria in animal and

plant cells

Eukaryotic cells contain many internal membranes

Your body without energy 8

9

The Evolution of Chloroplasts and Mitochondria

Unit 2

10

Photosynthesis: a process in plant cells

and other organisms to convert light

energy into chemical energy.

Chemical energy is stored in the bonds

of carbohydrate molecules.

Chloroplasts manufacture sugar

11

Cellular respiration: a process used by

plant and animal cells to release

the chemical energy stored in the

bonds of carbohydrate molecules and

partially capture it in the form of ATP.

Mitochondria produce chemical energy

12

Mitochondria:

• look like bacterial cells

• about the same size as bacterial cells

• have their own circular genome

• produce the enzymes necessary for

protein synthesis

Prokaryotes within our cells?

MM

MMMM

Did bacterial cells take up residence

inside a proto-eukaryotic cell?

Eukaryotic cells benefit from bacterial processes 13

Anaerobiceukaryote

Aerobicbacterium

2. Bacterium liveswithin eukaryoticcell.

1. Eukaryotic cellsurrounds andengulfs bacterium.

3. Eukaryote suppliesbacterium with protectionand carbon compounds.Bacterium supplieseukaryote with ATP.

Pyruvate and O2

Endosymbiotic theory of organelle evolution 14

DNAAncestral prokaryote

Nucleus

Aerobic heterotrophic prokaryote

Mitochondrion

Photosynthetic prokaryote

Ancestral photosynthetic eukaryote

Ancestral heterotrophic eukaryote

Plastid

Quiz One 15

16

Evidence Supporting the

Endosymbiotic Theory of

Organelle Evolution

Unit 3

17

Prediction: You might see living

examples of acquired endosymbiotic

relationships which can be seen in

eukaryotic organisms.

Endosymbiotic theory of organelle evolution

Phagocytosis by an early eukaryote: a first step in the origin of plastids

Endosymbiosis in action 18

Cyanobacterium(predecessor of plastid)

Feeding channel

Nucleus

Permanent food vacuole

19

Corals are animals that

live symbiotically with microbes. This

is similar to the human microbiome!

Endosymbiosis in action

This sea slug is an animal that can

consume a photosynthetic algae and

keep only the chloroplasts.

20

The Endosymbiotic theory of organelle evolution

states that these temporary relationships are

permanent and heritable.

Consistent with this theory, the same proteins

and genes should be found in bacteria,

chloroplasts and mitochondria.

Endosymbiotic theory

21

Organelle membranes allow for

compartmentalization.

Organelles are a distinct domain within a

cell with a specific function.

Different compartments contain:

• a unique set of enzymes

• produce and contain different products

Increased membrane surface area can:

• increase the potential metabolic capacity

across the membrane

Why are organelles important?

Quiz Two 22

23

Cellular Respiration

Unit 4

How does energy flow in biological systems? 24

Light energy

Photosynthesis in chloroplasts

Cellular respiration in mitochondria

ECOSYSTEM

Heat energy

Organic molecules + O2CO2 + H2O

ATP powers most cellular work

ATP

Chloroplasts make chemical energy 25

Photosynthesis: the process of using sunlight to produce carbohydrates

6CO2 + 12H2O + light energy --> C6H12O6 + 6H2O + 6O2

Some organisms do not eat. For example, plants capture light energy and make carbohydrates

26

Monosaccharides polymerize via glycosidic linkages to form disaccharides

Carbohydrates can be used to make ATP

Monosaccharides Disaccharide

+ + H2O

Plants and animals store polysaccharides for energy 27

Polysaccharide Chemical Structure 3-D Structure

Starch:Used for energy storage in plant cells

Glycogen:Used for energy storage in animal cells

Unbranched helix(amylose)

Highly branched helices(Glycogen)

α-Glucose α-Glucose

α-Glucose α-Glucose

Glucose processing produces most of the electron carriers that are used to make ATP.

Glucose processing produces ATP 28

2 NADH

2 CO2

2 Acetyl CoA 4 CO2

6 NADH2 FADH2

2 ATP

Glucose 2 Pyruvate

2 NADH

2 ATP

Citric Acid Cycle

29

The electron transport chain

establishes a proton gradient that is

used to produce ATP in the

mitochondria.

A proton gradient drives the synthesis of ATP

Proteins and fats can also be processed as fuel 30

Fats

Carbohydrates

Proteins

Fattyacids

Glycerol

Sugars

Amino acids

GlucoseGlycolysis

Pyruvate Acetyl CoA Krebs cycle

ATP Hydrolysis is an exergonic reaction

Energy can be released by hydrolysis of ATP 31

30.5 kJ/mol ATP

+ H2O

+ +

ATP ADPInorganic

phosphate

Energy

ATP is important for many cellular processes 32

ATP

Mechanical work

Contracting a muscle

ATP

Transport work

Active transport

ATP

Chemical work

Building a large molecule

33

Endomembrane system: a group of

organelles in eukaryotic cells that

performs most lipid and protein

synthesis; endoplasmic reticulum (ER),

Golgi apparatus, and lysosomes.

The evolution of an endomembrane system

Quiz Three 34

• Endosymbiotic relationships have led to the evolution of organelles

essential for energy acquisition.

• The acquisition of energy by these organelles is dependent upon

proteins embedded in the membranes.

• Metabolism of carbohydrates requires proteins called enzymes.

Conclusions 35