Introduction to Cell Physiology

Introduction to Cell Physiology

Slides by John R. Waters, Anatomy and Physiology at Penn State

available at: www.bio.psu.edu/Courses/Fall2002/Biol141-Everything/powerpoint/All_the_intro_concepts_SummerB/

What is physiology?

• The branch of biology dealing with the functions and activities of living organisms and their parts.

• The study of bodily function that primarily employs the methods of experimental science.

Biological Organization (pg.17)A hierarchy of structural complexity

• The organism,

Biological Organization (pg.17)A hierarchy of structural complexity

• The organism is composed of organ systems

Biological Organization (pg.17) A hierarchy of structural complexity

• The organism is composed of organ systemsorgans systems are composed of organs,



organs are composed of tissues,



organs are composed of tissues,tissues are composed of cells,




cells are composedpartially of organelles,





organelles are composed ofmolecules,






molecules are composed

of atoms,






molecules are composedof atoms,

and atoms are composed ofsubatomicparticles

Chemical Bonds (58-60)

• Atoms can be bound together to form molecules

– 2 H+ + O-- H2O (water)

– Na+ + Cl- NaCl (sodium chloride)

– 6 C + 12 H+ + 6 O-- C6H12O6 (carbohydrate)

Chemical Bonds (58-60)

• The atoms that form molecules are bound together by chemical bonds– covalent bond

• electrons shared between atoms– single (C-C)– double (C=C)– non-polar (C-C)– polar (O-H)

» water

– ionic bond

• oppositely charged ions are attracted to one another– NaCl

– hydrogen bond

• weak bond between a slightly positive hydrogen and a slightly negative oxygen or nitrogen

OHH

-

+

Chemical Bonds - hydrogen bonds (58-60)

– hydrogen bond

• weak bond between a slightly positive hydrogen and a slightly negative oxygen or nitrogen

OHH

-

+

Molecules and chemical reactions (66, 68)

• Chemical bonds between molecules can be formed or broken during chemical reactions

• Metabolism is all of the chemical reactions occurring in your body– catabolism (breaking down a molecule)

• energy released during chemical reaction

• EX. carbohydrates are broken down to release energy

– anabolism (synthesizing or building a molecule)• energy required for chemical rxn

• EX. energy is used to build proteins or make ATP.

Molecules and chemical reactions – ATP (96-97)

• ATP (adenosine triphosphate) is a molecule synthesized by organisms to store energy in a readily usable form.

• The energy is stored in the chemical bonds of ATP molecules as chemical potential energy– ADP + P + energy -> ATP

• This energy can be used by cells whenever they need to do work.– ATP -> ADP + P + energy

Molecules and chemical reactions – ATP (96-97)

Life requires about 25 chemical elements

• 96% of living matter is made up of– C– O– N– H

• the other 4% is mostly P, S, Ca, and K

• plus some trace elements like Fe and I

Most macromolecules are polymers (80)

• Monomers are basic subunits used to build polymers(smaller molecules) (larger molecules)– We will focus today on two polymers

• lipids• proteins

Lipids are mostly hydrophobic molecules with diverse functions (85-87)

• Fats


• Phospholipids


• Phospholipids form stable structures in water

Proteins (87-92)• Proteins are the molecular tools for most

cellular functions• A protein is a polymer of amino acids

connected in a specific sequence

N

H

C C

H

O

OH

H

R1

N

H

C C

H

O

OH

H

R2


cellular functions

• A polypeptide is a polymer of amino acids connected in a specific sequence

N

H

C C

H

O

OH

H

R1

N

H

C C

H

O

OH

H

R2

+

N

H

R1

C C

H

OH

N

H

R2

C C

OH

OH

HOH+


cellular functions


• 20 different amino acids (aa)

• Each aa has a differentR group


cellular functions



• Each aa has a differentR group– Polar (+ or - charge)

• hydrophilic


cellular functions



• Each aa has a differentR group– Polar (+ or - charge)

• hydrophilic

– Non-polar (no charge)• hydrophobic

– hydrogen, ionic, covalent bondsbetween R groups are also possible

Proteins (87-92)

• A protein’s function depends on its specific conformation– primary structure– secondary structure – tertiary structure– quaternary structure

• Proteins are the molecular tools for most cellular functions


A molecule’s biological function is related to its shape

Remember….

A protein’s function depends on its specific conformation




Review

Biochemical Example of Feedback Control

InputInput(Glucose)(Glucose)

X0 X1 Xi Xn… …Output(ATP)

perturbation

Negative FeedbackNegative Feedback

Glycolysis: a metabolic pathway

X_i : metabolites (small molecules derived from glucose)

: chemical reactions (each catalyzed by an enzyme)

Enzyme-Catalysed Reactions

http://www.uyseg.org/catalysis/principles/images/enzyme_substrate.gif

http://www.eccentrix.com/members/chempics/Slike/Enzyme/2Competitive_inhibition.jpg

Allosteric Regulation

http://courses.washington.edu/conj/protein/allosteric.gif

A Regulated Enzyme: Phosphofructokinase (PFK)

Effector:

Product:

Reactants:

How can biochemicals regulate enzyme activity?

By inducing conformational changes

Nucleic acids store and transmit hereditary information

A DNA strand is a polymer with an information-rich sequence of nucleotides

The DNA strand is a double helix

Central Dogma

DNA (deoxyribonucleic acid)

http://genetics.gsk.com/graphics/dna-big.gif

Chain composed of bases: A, C, G, T

Some segments of DNA code for proteins

http://www.designeduniverse.com/articles/Nobel_Prize/trna.jpg

Other segments of DNA code for RNAs (e.g. tRNAs or rRNAs.)

Still other segments of DNA are regulatory regions.

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/repressor_1.gif

Repression Activation

Basic structure of a cell (104-108)

• plasma membrane

• cytoplasm– organelles

• vesicles

• mitochondria

• nucleus

• many others

– proteins• structural

• enzymes

Basic structure of a cell - plasma membrane (108-112)

• lipid bilayer

• membrane proteins– gates/pores– pumps– receptors

• Plasma membranes will let some things pass, but not others

• They are semipermeable

Carrier mediated transport (128-131)• Requires membrane proteins• Two types of carrier mediated transport

– facilitated diffusion• proteins channels just act as doors• just diffusion• no energy required

– active transport• substances moveagainst theirconcentration gradient

• move from an areaof low concentration...

• to an area of high concentration

• Requires ENERGY

ATP

Active Transport Review (128-131)

Documents

Introduction to Cell Physiology