chapter 2 spring 2013 posting.ppt

7/27/2019 Chapter 2 Spring 2013 posting.ppt

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Chapter 2

Molecules, Cells

and Theories


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Molecules, Cells and Theories

Overview

Biomolecules

The Cell

Theories of Aging


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Cells contain anaqueous solution,with 1000s of solutes:

single atoms (electrolytes)

small molecules large molecules

SUPER KEY CONCEPT


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Water

Composition of Tissue (by weight)


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FOUR Major Classes o f

Biomolecu les?


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FOUR Major Classes of

Biomolecules

proteins

carbohydrates

lipids

nucleic acids

MOST respons ib le fo r LIFE?


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Water

Life by Purves, 7th Ed. Figure 3.2



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Water



SIX basic nu tr ien ts?


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Water



HOW do large biomo lecu les

get to BE so large?


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Large biomolecules arepolymers(molecular chains).

KEY CONCEPT


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You ARE what you eat, but


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food monomers new polymers

hydro lys is

DIGESTION ANABOLISM

(within gut) (within cells)

You ARE what you eat, but


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There are TWO TYPES of

metabolismin the cell:

anabolism

? ? ?

catabolism ? anabolism

KEY CONCEPT


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CHON

Biomolecules Primarily Consist

of FOUR Different Atoms


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Biomolecules

proteins

carbohydrates

lipids

nucleic acids


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1. Structural Proteins: form structural

components of the cell.

2. Enzymes: speed and regulate

biochemistry.

Two Main Types


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KEY CONCEPT

The 3D shape of proteins isESSENTIAL for their function

it allows it to INTERACT with a

specific molecule.


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A Polypeptide


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What causes a protein to fold?


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Folding occurs SPONTANEOUSLY,

based on the amino acid sequence.

Environmental factorsalso affect the

conformation.

Key Concept


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Proteins Have FOUR Levels


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Proteins Have FOURLevels

of Structure


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Protein Conformation


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Making proteins is ANABOLIC.

Where does the ENERGY

come from???


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Biomolecules

proteins

carbohydrates

lipids

nucleic acids


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Carbohydrates

sugars and sugar polymers

monosaccharides

polysaccharides

FUNCTIONS: energy ANDstructure


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Glucose


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Polysaccharides


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Biomolecules

proteins

carbohydrates

lipids

nucleic acids


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Lipids

molecules that are mostly H and C

Functions:

1) energy source (fats)

2) structural (phospholipids)3) cholesterol and its derivatives


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Triglyceride


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Saturated?

Unsaturated?


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Phospholipid


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Hydrophilic AND Hydrophobic

Fig 5.13


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Cholesterol


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Nucleic Acids

nucleotides 4 different ones

polynucleotide

two types

Functions: information storage (polynuc leot ides)


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Nucleic Acids


polynucleotide

two types


energy source (a nucleot ide)


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Nucleic Acids


polynucleotide

two types


energy source (a nucleot ide: ATP)


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ATP


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DNA RNA protein

WHY?


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DNA RNA protein

WHY?

How many X genes do we have??


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The Central Dogma

transcription translation

a gene mRNA polypeptide

DNA RNA protein

replication


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RECAP

1. Cells are constructed for FOUR main

types of biomolecules.2. The most complex are proteins, which

provide both structure and function.

3. Genes(DNA) provide the instructions

to make all proteins.


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The Central Dogma

a gene mRNA polypeptide

DNA RNA protein

replication


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The DNA is Organized

It is not just one long strand!

It is organized into distinct units

called CHROMOSOMES.

How are the TERMS related?

RELATIONSHIPS


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Chromatin(size = large)

All genetic material in the nucleus

3 x 109base pairs

The DNA from ONE cell stretched out wouldbe about 6 feet long.

RELATIONSHIPS

RELATIONSHIPS


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RELATIONSHIPS

CHROMOSOME(size = medium)

DNA/PROTEIN structures carrying GENES

1 x 106-7nucleotides per chromosome 23 PAIRS in humans


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The essential

GENOME

no pairs!


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GENE(size = small)

nucleotide sequence of DNAthat controls ONE

hereditary characteristic of an organism.

encodes an RNA molecule (Ex: mRNA)

~ 1 x 104 5 x 105bp per gene


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ATATGCATGCAGATATACGTACGTCT

CHROMOSOME

GENE

CHROMATIN

RELATIONSHIPS


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Heterochromatin

Tightly PACKED chromatin, notavailable for gene expression.

M l l C ll d Th i


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Overview

Biomolecules

The Cell

Theories of Aging


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Cell Membrane

A barrier to maintain the cells internal

chemistry.

Made up of:1) phospholipids

2) diverse proteins

Also provides broad FUNCTIONALITY:Ex: transport, receptors, joining cells

C


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Cell Membrane


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Mitochondria

Use sugar, fat and protein tomake ATP.


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Once an ancient BACTERIAL CELL!

Orig in of Mi tochondr ia?


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Once an ancient BACTERIAL CELL!

Have their own DNA!

Orig in of Mi tochondr ia?


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Allow for the MANUFACTURE and

SECRETION of biomolecules.

ER and Golgi


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Lysosome

Life by Purves, et.al., 7th Ed. Figure 7


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Gives SHAPE/SUPPORT as well as

additional functionality to the cell.

Cytoskeleton


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Cytoskeleton


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Our Multicellularity

= ?


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1. Cells + other structure.

2. Also: empty space!

Multicellularity


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Intercellular Materials

1. Amorphous Materials: vary in theirwater/protein content

Ex: blood

Ex: cartilage

Ex: bone

2. Fibers

a) Collagen: fibers twisted into thick cables

Ex: tendons, ligaments, bone

b) Elastin: more flexible

Ex: dermis skin, ears


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WHY do cells d iv ide?

1) Growth/development

2) Repair/regeneration

3) Reproduction


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Cells Reproduce byMitosis

1. Chromosomes are duplicated by DNAreplication.

2. Pulled apart by the cytoskeleton,which also pinches cell in half.

C ll C l


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Cell Cycle


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Do ALL cel ls div ide?

The frequency of mitosis

depends on cell type.


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G0

Frequency of Mitosis Depends


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1) Continuous

2) Based on need

3) Rare/never

Go applies to 2 and 3

Most human cells are in Go

Frequency of Mitosis Depends

on Cell Type

K C t


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Replicating a chromosomes ENDS

(telomeres) requires a special enzyme:

Telomerase

Without this enzyme, a cells ability toproliferate is limited!

Key Concept

K C t


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The cells of humans and otheranimals CANNOT DIVIDEINDEFINITELY in culture.

The # of rounds of cell division

characteristic of that cell type is theHayflick Limit.

It decreases as an organism ages!

Key Concept

Molecules Cells and Theories


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Overview

Biomolecules

The Cell

Theories of Aging

Key Concept


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Numerous theories have been

proposed to explain biological aging.

= hypotheses

overlap

aging may involve several/all/(none?)

Key Concept

Why consider aging from an


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y g g

evo lut ionary standpo int?

Nothing in biology makes senseexcept in the light of evolution.

--1973 Essay byTheodosius Dobzhansky

E l ti


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Evolution

The change in the genetic compositionof a population from generation to

generation, that over time brings aboutnew species.

Occurs by mutation.

Proceeds by natural selection.

survival of the fittest

= reproductive success!

Why isnt aging ELIMINATED


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y g g

by evolu t ion?

An organism is no longer neededfollowing successful reproduction!

= selfish gene theory (Dawson)

Limited resources may have resultedin a BALANCE b/w the genes forSURVIVAL (defense/repair) and genesfor REPRODUCTION.

Three Criteria for Valid Theory


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1) The changes addressed mustoccur COMMONLY in all members

of the species.2) The process must be

PROGRESSIVE.

3) The process must lead to ORGANDYSFUNCTIONS that ultimatelylead to failure of organ/system.

Three Criteria for Valid Theory

Three Main Groups of Theories


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1) Aging results from WEARING OUTof an organ/system.

2) Aging results from nonreversibleCHEMICAL CHANGES within cellsthat alter its functioning.

3) Aging is programmed by aBIOLOGICAL CLOCK, located in asingle center or in each cell.

Three Main Groups of Theories

Theories of Aging


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Theories of Aging

1. Genetic

2. Rate of Living

3. Free Radical

4. Mitochondrial

5. Clinker

6. Cross-Linkage

7. Immune Deficiency

8. Wear and Tear

Genetic Theories


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Genetic Theories

1. Death Gene Theory

2. Telomere Theory

3. Somatic Mutation

4. Faulty DNA Repair

5. Error Catastrophe

Death Gene Theory


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Death Gene Theory

A SET OF GENES activates late in life,

and tells the body to deteriorate anddie.

Cou ld genes invo lved in age-related

diseases BE the death genes?

Telomere Theory


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Telomere Theory

Shortening of telomeresaffects the

expression of certain genes.

Ex: through heterochromatin unwinding

May occur at DIFFERENT RATES indifferent tissues!

Somatic Mutation Theory


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Somatic Mutation Theory

Harmful factors may INJURE GENES.

Ex: radiation, toxic chemicals, freeradicals

Simplistic, but may be combine/contribute to free radical and faulty DNArepair theories.

Faulty DNA Repair Theory


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Faulty DNA Repair Theory

DNA damage is repaired EARLY in life.

Over time, the repair mechanisms

begin to fail.

Error Catastrophe Theory


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Error Catastrophe Theory

Damage to RNA and protein result in

biological aging.

EX: protein synthesis proteins, leadingto accumulation of mistakes

Disproven!

RECAP: Genetic Theories


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2. Telomere Theory

3. Somatic Mutation4. Faulty DNA Repair


Which involves a programmed

BIOLOGICAL CLOCK?



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2. Telomere Theory



Which invo lve(s) non reversib le

CHEMICAL CHANGES in cel ls?



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2. Telomere Theory



Which invo lve(s ) WEARING

OUT of an organ/system?



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2. Telomere Theory



Which has been DISPROVEN?



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2. Telomere Theory



Which has been reworked

in to *FR and FDR?

Theories of Aging


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Theories of Aging

1. Genetic

2. Rate of Living

3. Free Radical

4. Mitochondrial

5. Clinker

6. Cross-Linkage

7. Immune Deficiency

8. Wear and Tear

Rate of LivingTheory


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Metabolic rateis DIRECTLY related to the

rate of aging, and INVERSELY related to

life span.Animals can use only a FIXED AMOUNT

of calories/oxygen in their lifetime.

DISPROVEN: by comparison of different

organisms, etc. May combine/

contribute to *FR and mito *FR theories!

Free Radical


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Free Radical

An atom/molecule with an ODD number

of esan unpaired electron (*FR).

Ex: *O2, *OH

highly reactive! occur naturally (Ex: in the presence

of oxygen, high glucosevia ROS)

implicated in more than 60 disordersEx: heart disease, cancer, Alz dis

damages lipids, proteins, and DNA

eliminated by antioxidants


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Free Radical Theory


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Free Radical Theory

FREE RADICAL DAMANGE is a OR themain reason for biological aging andrelated diseases.

TO:

lipids: membrane permeability,mitochondrial energy production,

atherosclerosis, more *FR proteins: disrupts enzymes, structure

DNA: slows cell division, promotescancer

Mitochondrial Theory


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MitochondrialTheory

Mitochondrial activity AND damagecause aging. Ties FREE RADICALTHEORY to mitochondria!

Ex: mitochondria are a main source of*FRs!

Ex: *FRs damage mitochondria

Ex: Radiation/chemicals damage mito Ex: damage accumulates over time

Ex: mito have DNA

Ex: mito DO NOT have DNA repair


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Clinker Theory


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ClinkerTheory

Waste products accumulate in cellsover time. (Cellular garbage theory)

Simplistic, but may be combine/

contribute to C-L theory.

Ex: accumulation of misfoldedproteins.

Cross-Linkage Theory


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Cross Linkage Theory

Post-translational modification toproteins resulting in irreversiblechanges to their structure, occurringover time. Affects flexibility/functioning/

size of tissues and body parts. Broadeffects: skin, arteries

Due to: free radicals and glucose

Glycation


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Glycation

Covalent joining of a sugar(Ex: glucose) to a protein via

particular amino acids.

without an enzyme

(vs. glycosylation)

Cross-Linkage Theory


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Cross Linkage Theory

Post-translational modification toproteins resulting in irreversiblechanges to their structure, occurringover time. Affects flexibility/functioning/

size of tissues and body parts. Broadeffects: skin, arteries

Due to: free radicals and glucose

Esp. affects diabetics!Ex: enzymes

Ex: collagen (~ 30% of bodys proteins!)

Ex: agg of proteins leads to neurodeg disease

Immune Deficiency Theory


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Immune Deficiency Theory

Over time, immune system begins todamage YOUR tissues(autoimmunity).

Wear and Tear Theory


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Wear and Tear Theory

An accumulation of injuries adverselyaffects the tissues/bodies.

Which theory is co rrect?


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Which theory is co rrect?

Aging may be due to aCOMBINATION of these or still

other causes!

some more/less important?

a chain reaction cause/effect?

chapter 2 spring 2013 posting.ppt

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