BIO101 Lecture-2 Jan 23, 2013.pdf

7/29/2019 BIO101 Lecture-2 Jan 23, 2013.pdf

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Lecture 2

1. Molecules of Life2. Cells & Biodiversity

BIO101 Introductory Biology

January 23, 2013


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Generic Definition

An organized genetic unit that is capable ofmetabolism,

reproduction and division
http://rds.yahoo.com/_ylt=A0WTb_3YOzlNlCwAv0ejzbkF/SIG=13bq3pq5u/EXP=1295682904/**http:/faculty.biu.ac.il/~gariniy/images/What%20is%20life%20-%20Schrodinger.jpg


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Proteins (summary)

Amino acids - 20

Peptide bonds

Polymer of amino acids

(hencepolypeptide)

1, 2, 3 and 4 structures 2: a-helix and b-sheet

Different shapes

Function is associated with structure

Most enzymes are proteins


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Carbohydrates

Different forms of glucose

Act as source of energy

Serve as building blocks of other molecules


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Simple sugars(Monosaccharides)


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Disaccharides

Maltose can be hydrolyzed by the human body but not cellobiose!


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Polysaccharides

Starch & glycogen

Glucose polymers witha-linkages

CelluloseGlucose polymers with

b-linkages


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Modified Carbohydrates


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Lipids

Hydrophobic (water hating) Energy reservoirs

Serve as thermal insulation

Repel water on surfaces of skin, fur and feathers

Play important structural role in membranes

Help capture light energy

Act as electrical insulator in nerve cells

Steroids and vitamins


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Simple lipids- Triglycerides (made up of glycerol + fatty acid)

-


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Fatty acids can be saturated or unsaturated


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Phospholipids


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Carotenoids & Steroids

- Produced from covalent linking and modification of isoprene units

Carotenoids

Pigments that trap light energy

Found in plants and animals

Vitamin-A Rhodoprin


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Steroids

Signal molecules

Similar chemical skeleton

Different types


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Some Lipids are Vitamins

Vitamin-A (precursor of -carotene)

Part of rhodopsin (required for vision)

Vitamin-D

Regulates absorption of calcium from small intestine

Vitamin-E

Protects cells from damaging effects of redox reactions

Vitamin-KInvolved in blood clotting


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Rhodopsin


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Nucleic Acids

Deoxyribonucleic (DNA) & Ribonucleic (RNA)

Basic unit: Nucleotide

Nucleotide has three components:

1. Sugar: Ribose (RNA) or Deoxyribose (DNA)

2. Base:

Purines: Guanine (G) and Adenine (A)

Pyrimidines: Thymine (T), Cytosine (C) & Uracil (U)3. Phosphate

Polymers of nucleotides (polynucleotides)

DNA is a double-helix

Complimentarity (G:C and A:T or A:U pairing)

Polarity (i.e., direction)

Store/carry genetic information


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http://upload.wikimedia.org/wikipedia/commons/8/81/ADN_animation.gif


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Figure 4-3 Molecular Biology of the Cell( Garland Science 2008)

DNA


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RNA

Mostly single-stranded Uracil (instead of thymine)

Ribose

Sequence

Structure


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Life (7th Ed)

Chapter 2: Small Molecules; p15-34

Chapter 3: Large Molecules; p35-60

Reading


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Cells

Fundamental units of life All organisms are composed of cells

All cells come from pre-existing cells

Require energy

Two types:- Prokaryotic (lacking nucleus)

- Eukaryotic (eu = true karyon= kernel)

Jargon: unicellular; multicellular


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The Scale of Life


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Visualizing

Cells by

Microscopy


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Features of Prokaryotic & Eukaryotic cells


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Prokaryotic Cells - Features


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Flagella and Pili


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Eukaryotic

Cells

Types

Animal cells

Plant cells


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Plant

Cells


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Nucleus- Contains DNA

- DNA is bound

to proteins

- Careful packaging!

- Nucleosomes


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Chromatin and Chromosomes

Heterochromatin Condensed chromosomal regions

Euchromatin Loose chromosomal regions

Endoplasmic Reticulum


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Endoplasmic Reticulum

Inside area Lumen

~1/10 volume of cell

Extensive surface area

Types

1. Rough protein intake & modification; transport

2. Smooth lipid & steroid synthesis; glycogen hydrolysis


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Golgi Apparatus- Cisternae (cis and trans)

- Receives proteins from ER for further modification

- Concentrates and packages proteins to destinations within and outside the cell


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Lysosomes- 1 mM diameter with featureless interior

- Contain digestive enzymes

- Sites where macromoleculesare broken down

- Process phagocytosed (i.e., eaten) stuff

- Primary and secondary

- Acidic environment

- Tay Sachs disease


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Mitochondria

- Powerhouse

- Bacterial origin

- ~1000 / liver cell- Outer & inner membranes

- Cristae

- Respiration

- Have their own ribosomes and DNA

- mtDNA is maternally inherited


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Chloroplasts Contain chlorophyll

Site of photosynthesis

outer & inner membrane

Origin of Mitochondria


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Figure 1-34 Molecular Biology of the Cell, Fifth Edition ( Garland Science 2008)

Origin of Mitochondria


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Peroxisomes

- Degrade hydrogen peroxide

Fractionating


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Fractionating

Cells and Cellular

Components

C t k l t


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Cytoskeleton

- Maintains cell

shape & support

-Ropes

- Framework for

transport

Composed of:

1. Microfilaments

(actin)

2. Intermediate

filaments

(fibrous proteins)

3. Microtublues

(tubulin)


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Molecular MotorsDynein and kinesin

- Move along microtubules

Plant Cell Wall


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Plant Cell Wall

Composed largely

of cellulose


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CellsThis and That

Require free energy

Are surrounded by membranes

Contain informational and non-informational

macromolecules

Need to sense and communicate with their environment Depend on pathways for processing nutrients and waste,

and synthesis/breakdown of small/large molecules

Life-begets-life!

Synthetic cells? (not yet, possible, never)


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Tree of Life!

Microbes Rule!


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B t i C i Diff t Sh


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Bacteria Come in Different Shapes

Spherical

Rod-shaped

Spiral

Some bacteria


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Some bacteria

use flagella

for locomotion

i d i l ll ll


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Gram Stain and Bacterial Cell Wall

Gram stain is used for classifying bacteria!

E S


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ORGANISM TYPE ENERGY SOURCE CARBON SOURCE

Photoautotrophs Light Carbon dioxide(found in A, B & E)

Photoheterotrophs Light Organic compounds(some Bacteria)

Chemolithotrophs Inorganic substances Carbon dioxide(some B; most A)

Chemoheterotrophs Organic compounds Organic compounds(found in A, B & E)

Energy Sources


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Highly diverse group

Autoheterotrophs

Look like corkscrews

Extremely small

Mostly Gram-positive

Some form endospores

Live in hot & acidic places

Some methanogens;

Salt lovers (halophiles)

Charateristics


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Life (7th Ed)

Chapter 4: Cells (p61-84)

Chapter 27: Bacteria & Archaea (p524-540)

Reading

Documents

BIO101 Lecture-2 Jan 23, 2013.pdf