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Biology Exam Study Guide Unit 1
7 Characteristics of All Living Organisms
1
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Ordered Complexity
3
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Growth, Development, & Reproduction
5
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Homeostasis
7
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022 x 10^23 = 1 Mole)

Isotope
• Multiple forms of an element that differ in the number of neutrons

Hydrogen, Oxygen, Carbon, & Nitrogen
• 95% of all living organisms
• Hydrogen & oxygen occur in water
• Nitrogen occur in proteins
• Carbon is building block for living matter
• Essential for growth & function

Molecules
Molecule: 2 or more atoms bonded together
Molecular Formula: Subscript indicates how many atoms are present
Compound: Molecule composed of 2 or more elements

3 Types of Bonds
1
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Strongest chemical bond
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Iconic Bonds: formed when an element looses/gains an election
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Hydrogen Bonds: Weak polar covalent bonds, represented with dashed lines
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Solutions Vs
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• Solutes are the substances dissolved in solvent
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Carbohydrates
2
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Proteins
4
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Monosaccharides
- Simpliest sugars
- most common are 5 or 6 carbons
- different ways to depict structures (ring or linear)
B
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Polysaccharides
- Many monosaccharides linked together to form long polymers
Example: energy storage- starch, structural role- cellulose, glycogen

Lipids
• Composed predominantly of hydrogen and carbon atoms
• Hydrophobic (can not hydrogen bond) insoluble in water
A
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Fatty Acids
- Saturated: all carbons are linked by single covalent bond (Solid at room temperature)
- Unsaturated: contain 1 or more double bonds (liquid at room temperature)
C
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Protein Structure
- Primary: Amino acid sequence, determined by genes
- Secondary: folding, helices, pleated sheets, random coiled regions
-Tertiary: Folding gives complex 3 dimensional shape, final stage
- Quaternary: Made of 2 or more polypeptides
B
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Hydrogen bonds
2
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Hydrophobic Effects
4
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Disulfide Bridges

Nucleic Acids
• Responsible for storage, expression, and transmission of genetic information
• Two classes:
- Deoxyribonucleic Acid (DNA): stores genetic information coded in the sequence
of their monomer building blocks, double helix
- Ribonucleic Acid (RNA): involved in decoding this information into instructions
for linking together a specific sequence of amino acids, single stranded, produced by
copying DNA

Cell Theory
1
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cells are the smallest unit of living organisms
3
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Microtubules: dynamic and unstable, organizing center for animals
2
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Actin Filaments: Provide structure and mobility for cell

Moter Proteins
• Head, hinge, tail
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• Uses ATP as source of energy for promoting movement
• 3 different kinds of movement:
- moves the cargo from one location to another
- remains in place and cause the filament to move
- attempting to walk

Flagella and Cilia
• Flagella is longer than Cilia: single or in pairs
• Cilia is shorter than Flagella: covers parts or all surface of cell
• Cilia and flagella helps cell move from base to tip

Endomembrane System
• Nucleus, endoplasmic reticulum, golgi appartus (secretion, processing and protein
sorting), lysosomes (stomach of cell), vacuoles (storage), plasma membrane (use receptors, boundary between cell and environment)
• Nuclear Envelope: Double membrane structure enclosed nucleus, outer membrane is
continuous with endoplasmic reticulum membrane, nuclear pores provide passageways
• Chromosomes: Composed of DNA and protein protection, organization, and expression of genetic material, in nucleus
• Endoplasmic Reticulum: Membrane falttened and fluid filled, ER Lumen is enclosed
- Smooth ER: Lacks ribosomes
- Rough ER: Studded with ribosomes
• Semi Autonomous Organelles: Can grow and divide to reproduce themselves, depends on other parts of cells for internal components, mitochondria (outer and inner
membrane, powerhouse, makes ATP) and chloroplasts (Photosynthesis, found in
plants and algae)

Biological Membrane
• Basic framework of the membrane is the phospholipid bilayer
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• Fluid-Mosaic Model: membrane is considered a mosaic of lipid, protein, and carbohydrate molecules, membrane exhibits properties that resemble a fluid because lipids
and proteins can move relative to each other within the membrane

Proteins Bound to Membranes
• Integral Membrane Proteins
- Transmembrane proteins: one or more regions that are physically embedded in the
hydrophobic region of the phospholipid bilayer
- Lipid Anchors: Covalent attachment of a lipid to an amino acid side chain within a protein
• Peripheral Membrane Proteins
- Non covalently bound to region of integral membrane proteins that project out from
the membrane, or they are bound to the polar head groups of phospholipids

Membranes are Semifluid
• Fluidity: Individual molecules remain close, yet have ability to move
• Semifluid: most lipids can rotate freely around axis within leaflet
• “Flip Flop” of Lipids: from one leaflet to opposite leaflet
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Length of fatty acyl tails
2
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Presence of Cholesterol

Glycosylation
• Process of covalently attaching a carbohydrate to a protein or a lipid
10

- Glycolipid: carbohydrate to lipid
- Glycoprotein: carbohydrate to protein
• Can serve as recognition signals for other cellular proteins
• Often play a role in cell surface recognition
• Protection effects: cell coat or glycocais- carbohydrate rich zone on the cell surface

Phosopholipid Bilayer
• Hydrophobic interior makes formidable barrier
- Diffusion: movement of solute from an area of higher concentration to an area of lower concentration
- Passive Diffusion: Without transport proteins
• Selectively Permeable
- Structure ensures: essential molecules enter, metabolic intermediates remain, waste
products exit

Cells Maintain Gradients
• Transmembrane Gradient: concentration of a solute is higher on one side than other
• Ion Electrochemical Gradient: Both an electrical gradient and chemical gradient

Passive Transport
• Does not require an input of energy
• 2 types
1
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Facilitated Diffusion: Diffusion of a solute through a membrane with the aid of a
transport protein

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Active Transport
• Movement of a solute across a membrane against its gradient from a region of low
concentration to higher concentration
• Energetically unfavorable and requires input of energy
• 2 types:
1
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Secondary Active Transport: Use preexisting gradient to drive transport of solute

Tonicity
• Isotonic: Equal water & solute concentrations on either side of the membrane
• Hypertonic: Solute concentration is higher on one side of the membrane (more energy
on the inside)
• Hypotonic: Solute concentration is lower on one side of the membrane (more energy
inside)

Osmosis
• Water diffuses through a membrane from an area with more water to an area with less
water
• If solutes can not move, water movement can make the cell shrink or swell as water
leaves or enters the cell
• Osmotic pressure: tendency for water to move into any cell

Pores
• Extensive non polar regions within a transmembrane protein can create a pore
through the membrane
• Cylinder of beta sheets in the protein secondary structure called a B-barrell

Transport Proteins
• Enables biological membranes to be selectively permeable

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• 2 classes:
1
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- Most are gated (open or close)
- Lig and Gated
- Intra cellular regulatory proteins
- Phosphorylation
- Voltage-gated
- Mechanosensitve channels
2
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• 3 types of Transporters:
1
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Symporter/ Cotransporter: 2 or more ions or molecules transported in same direction
3

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