Biochemistry to Cells

Chapters 2 and 3

Anatomy is Structure, Physiology is function

• Anatomy– Study of internal and

external structure – i.e. structure of heart

and blood flow

• Physiology– Study of how organisms

perform specific functions

– i.e. how does the heart pump blood

Levels of Organization in the Body.

Inorganic versus Organic Compounds

Inorganic• Small molecules that

generally do not contain carbon and hydrogen atoms.

Organic• Molecules composed of

carbon and hydrogen molecules

• Larger and more complex than inorganic molecules

CarbohydratesSugars and Starches• Contain carbon, hydrogen

and oxygen in a 1:2:1 ratio• Main source of energy for

body• Monosaccharides

– Glucose, fructose, galactose• Disaccharides

– Lactose, maltose, sucrose• Polysaccharides

– Glycogen, starch, cellulose

Monosaccharides – building blocks for all sugars

From Monomers to Polymers

Dehydration Synthesis• Remove water to build large

molecules from smaller ones

• i.e. making proteins from amino acids

Hydrolysis• Split water to break down

large molecules into small• i.e. digestive tract

Lipids

Fats, oils and waxes• Contain large amounts of

carbon and hydrogen in a 1:2 ratio, but very little oxygen.

• Insoluble in water (hydophobic), makes a great barrier.

• Energy reserves, insulates and cushions organs

• Composed of fatty acid chains and glycerol

saturated

unsaturated

Saturated•No double bonds, all carbon atoms are saturated with hydrogen•Animal fats, are solid at room temperature•Large amounts in your diet increases the risk of heart diseaseUnsaturated•Contain at least one double bond• Most Plant oils, liquid at room temperatureTriglycerides are the most common fats in body.

Phospholipids How is structure related to function?

•Consists of a glycerol and two fatty acid chains linked to a phosphate group (PO4)•The phosphate group is attracted to water (hydrophilic), Why?•The fatty acid chains are hydrophobic. •Make up all cell membranes

Cell membrane composed of phospholipids and proteins.

Function?Structure?

ProteinsMost abundant organic compounds in the body

• Composed of amino acids, 20 different amino acids

• Structure of an amino acid– Amino group– H– Carboxyl group– R (remaining), varies from

one amino acid to another• Peptide bond joins two

amino acids together

Proteins• The structure of the

R group makes the amino acids different from each other.

• The R groups between the different amino acids help create the proteins shape.

• Folds and bonds form creating distinct protein shapes

Shape Determines FunctionStructure of a protein is determined by sequence of amino acids

• Proteins are made at the _________ and sent to the ____________ to be packaged into their specific shape.

• Small differences can have large effects… mutations

Formation of Proteins

Protein Function• Support: provide structure to cells and organs• Movement: contractile proteins in muscles• Transport: carrier protein found in cell

membranes• Metabolic Regulation: Enzymes speed up

chemical reactions• Coordination and Control: Protein hormones

influence the chemical reactions in cells• Defense: keratin in the skin, antibodies, clotting

proteins

Enzyme FunctionEnzymes are Proteins• Speed up chemical reactions in

a cell by reducing the activation energy needed to start the reaction.

• Enzymes control all life processes.

• Enzyme shape determines function.

• Shape of proteins can be altered by pH, temperature, or ion composition

Enzyme Function• Substrate – reactant that enzyme affects• Active site – region on enzyme that substrate attaches to.

– Lock and Key arrangement• Each enzyme catalyzes only one type of reaction (specificity)

Nucleic Acids: DNA and RNA

Basic building block is a nucleotide.

Structural similarities:

Structural differences:

Nucleus – Composed of Chromatin (DNA)

ChromatinDNA wrapped around 8 histone proteins, creates a subunit called a nucleosome.How tightly packed the DNA is around the nucleosome and its tails helps determine gene expression

Two Types of Chromatin

Euchromatin Heterochromatin

Transcription

Transcription – rewriting of DNA into RNA; controlled by RNA polymerase

Translation- changing the message of nucleic acids into an amino acid chain (protein)

Which nucleic acid carries the code for the protein?

Translation- occurs in the ribosome

Role of mRNA:tRNA:rRNA:Codons:Anticodons:

How is gene expression controlled in Eukaryotic cells?

Heterochromatin

• Epigenetics – study of changes in gene expression caused by histone modification and DNA methylation other than changes in the DNA sequence (mutations)

• Regulates gene expression w/o changing the DNA

• Changes have been shown to be heritable.

RNAi (RNA interference)• Double stranded RNA

molecules that inhibit gene expression (What?)

• Small interfering RNAs (siRNA) attach to mRNA

• The mRNA is then cut up by a number of enzymes (agronaute and dicer).

• Why does this affect gene transcription?

• What advantage doe s this give our cells?

Cells are composed of organic compounds.

ATP – energy currency for cell

• ATP → ADP + P• Energy is released

Mitochondria – Powerhouse of cell.How does form relate to function?

Cell Specialization