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Animal Physiology > Chapter 2 Molecules And Cells > Flashcards

Chapter 2 Molecules And Cells Flashcards

1
Q

What is this model? What is composed of?

A

Fluid mosaic model.

Lipid, proteins, and carbohydrates.

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2
Q

Phospholipid characteristics

A

Amphipathic: hydrophobic and hydrophilic

Polar head

Non-polar tail

  • Saturated if fatty acid tails do not have any double bonds
  • Unsaturated if double bonds are present
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3
Q

Phospholipid Characteristics 2

A

Phospholipids become more rigid when cold

Fish living in polar environments incorporate moreunsaturated fatty acids to prevent stiffness

unsaturated-double bond

saturated- no double bond

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4
Q

Cholesterol

A

Reduces the effect of temperature variations on membrane fluidity

Increases membrane fluidity by preventing phospholipids from being tightly packed

Provides rigidity at high temperatures

increases fluidity when cold and decreases it when warm

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5
Q

Types of membrane proteins and functions

A

Intergral and peripheral

channels, transporters (carriers), enzymes, receptors, and structural proteins.

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6
Q

Levels of protein structure

A

Primary - linear sequence of AA composing the polypeptide chain

Secondary- twist or bend upon themselves to form a more complex structure: alpha helix or beta pleated sheets (hydrogen bonds)

Tertiary-3d shape of polypeptide chain; unique for each protein (combo beta and alpha)

Quarternary- (hemoglobin)

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7
Q

Denaturation

A

the unfolding of proteins by hostile in enivorments

temp, pH,

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8
Q

Carbohydrates

A

Carbohydrates are covalently bound to proteins and lipids

Types

Glycoprotein

Glycolipids

Proteoglycans

Always on the outside of the cell and may serve as attachment sites for extracellular proteins and as cell-recognition sites

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9
Q

Epithelia

A

Forms a boundary by covering a body or organ surface or lining a cavity

Characteristics:

Cellularity

Polarity

Ennervated

Avascular

Regenerative

Supported by connective tissue

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10
Q

Epithelia

A
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11
Q

Junctions

A

Tight Junctions- hold cells together and prevents substances from passing between cells

Septate Junctions- found in invertebrates

Desmosomes- hold cells together and found in tissues that stretch

  • Skin
  • Heart
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12
Q

Junctions 2: gap junctions

A

Composed of connexons

  • Made up of connexins

Allows passage of small molecules from one cell to another

Electrical synapse (communicates with electricty)

6 protein subunits is a hemichannel

ions move through

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13
Q

Intercellular transport

A

Paracellular and Transcellular

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14
Q

Metabolism

A

All of the chemical reactions occurring within the animal

Main types

Catabolic- breaks down complex to simple

Anabolic- builds simple to complex

Metabolic rate: The speed of these reactions

Reactant concentration, temperature, particle size influence speed

speed can be increased by using enzymes

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15
Q

What are enzymes?

A

Catalysts that speed up reactions without being modified

  • Can be used to regulate the speed of chemical reactions
  • Reactions can go in both directions (Law of Mass Action) (tells which way a rxn goes)

Bind with, and act upon substrates to produce products

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16
Q

Enzymes Characteristics

A

Have 3D shapes

  • Substrates (ligands) bind at the active site
  • Weak, non-covalent bonds
  • May have more than one active site
  • Binding is specific due to chemical and electrochemical properties
  • Binding changes the shape of the enzyme
  • Cooperativity
  • Positive vs. negative
  • Homotropic vs. heterotropic

Allosteric regulation: Non-substrate binding alters catalytic rate

17
Q

Enzyme kinetics

A

Enzymes display saturation kinetics

Maximum velocity determined by:

  • Enzyme quantity
  • Enzyme effectiveness

Hyperbolic (Michaelis-Menton)

  • Enzyme usually has 1 binding site

Sigmoid

  • Enzyme has multiple binding sites
18
Q

Enzyme kinetics continued

A

Affinity

Probability that an enzyme and substrate interact to form a complex

  • At normal substrate concentrations, high affinity enzymes produce a faster reaction velocity

Apparent Michaelis Constant (Km)

  • Substrate concentration needed to attain 50% of Vmax
19
Q

Enzymatic regulation of cell function

A

Two Methods

  1. The types and amounts of enzymes within a cell determine which metabolic pathways are functional
  • Constitutive vs. inducible enzymes
  • Controlled by gene expression and degradation
    • Promoters, enhancers, and transcription factors
  1. The activity of the enzymes may be altered to control the rate of the metabolic pathways
  • Allosteric and covalent modulation
    • Upregulation/downregulation
    • Feedback inhibition
  • Rate-limiting and branch-point enzymes are strategically important
20
Q

Isozymes

A

Isozymes:Different forms of an enzyme within a species

Interspecific enzyme homologs: Different forms of an enzyme encoded by homologous genes in different species

Multiple forms of an enzyme occur at all levels of organization

Several types of one enzyme catalyze the same reaction

  • Amino acid sequences differ
  • Many forms have evolved due to genetic mutations
  • May have different regulatory and catalytic properties
21
Q

Protein Maintenance

A

Many stresses can denature proteins such as enzymes, making them nonfunctional

  • Temperature
  • Low cellular levels of O2
  • Toxic chemicals

Molecular chaperones can correct reversible denaturation

  • Also active when proteins first made
  • Heat shock proteins are best known examples
22
Q

Protein Maintainance Continued

A

The ubiquitin-proteasome system

Destroys unnecessary proteins

  1. E1 activates ubiquitin
  2. E2 attaches ubiquitin to a lysine within the target protein (polyubiquination may occur)
  3. The tagged protein is chopped into smaller proteins by a proteosome
  4. Peptidases break down the smaller proteins into amino acids
23
Q

Protein Synthesis

A

Transcription- synthesis of mRNA from DNA

Regulated by DNA promoters and transcription factors

Translation- protein made from mRNA template

Occurs on free ribosomes

  • Protein goes to nucleus, mitochondrion, or cytoplasm

Occurs on rough endoplasmic reticulum

  • Protein is destined for lysosome, secretion, or plasma membrane

Regulation

  • Translation can be globally regulated
  • Specific regulation by mRNA 5’- and 3’- UTR sequences

Animal Physiology (5 decks)

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