Lecture 4+5 (Bio-2210)

Polysacchrides

long-chains of sugars and sugar derivatives, it is not encoded by DNA

Polysacchrides energy source in plants

Starch

Polysacchrides energy source in animals

glycogen

Polysacchrides cell storage in plants

cell wall

Polysacchrides cell storage in animals

exoskeleton of arthropods

common monosaccharides

glucose, fructose, galactose

the most common monosaccharide in the cell

D-Glucose

Where did the name Carbohydrate come from

• the formula C_nH_2nO_n

• Every carbon is “hydrated”

Glucose Structure

• exist in linear and ring form

• have alpha and beta rings and linkages

• attached by glycosidic bonds

what kinds of glucose is starch and glycogen

both alpha-D-glucose with alpha glycosidic bonds that can be broke down into glucose

why are polysaccharides highly branched

gives more ends for glucose to release from for energy

Amylopectin

in starch, has similar branching structures and functions and glycogen

starch structure

• branches every 12-25 units

• branches are about 20-25 units long

Glycogen structure

• branches every 8-10 units

• branches are 8-12 units long

what decides the identity and function of a Polysacchrides

1. monomers used

2. type of bond

3. amount/length of branches/chain

what determines the structure of a Polysacchrides

1. amount of hydrogen bonding

2. strength/rigidity of structural Polysacchride

Lipids

Not formed by linear polymerization

functions of Lipids

• membrane structure

• energy storage

• signal transmission

Key features of Lipids

• all are at least partially hydrophobic

• some are amphipathic

Fatty Acids

• components of many Lipids

• unbranched chains of 12-20 hydrocarbons with a carboxyl group at one end

• The non-polar chain is the “tail”

• they are highly reduced to yeild lots of energy upon oxidation

Fatty Acids saturated structure

has the most hydrogens possible, all single bonds

Fatty Acids unsaturated structure

has one or more double bond causing it to bend

Triglycerols

• storage lipids

• a glycerol with 3 Fatty Acids attached

• fatty tails are oxidized for energy

Phospholipids

• contains two Fatty Acids (tail) and a phosphate with a polar alcohol (head)

• amphipathic (critical for membrane function)

Phosphoglycerides

predominant phospholipids in most membranes

sphingolipids

• specialized lipids, roles in membrane organization/signalling

• similar to phosphoglycerides but with a sphingosine backbone

Glycolipids

• specialized lipids, roles in membrane organization/signalling

• carbohydrate head rather then phosphate

Steriods

derivatives of four-ringed hydrocarbons

• classified as lipids since they are nonpolar

• sterols

Sterols

steroids with alcohol groups

Cholestral

the most common animal steroid

Steroid Hormones

used in cell communication

• ex. Extradiol, Testosterone

Cell Theory

1. all organisms consist of one or more cells

2. the cell is the basic unit of structure for all organisms

3. all cells arise from only preexisting ones

the four phases of cell appearance

1. abiotic synthesis of simple organic material

2. abiotic polymerization of these macromolecules

3. Emergence of a macromolecule capable of replication and storing genetic information

4. encapsulation of the first living molecule with a simple membrane

Stanley Miller, 1953

Simulated the atmosphere of early Earth, using lightning as a catalyst. the result was two simple amino acids (Abiotic organic synthesis)

Predominant Theory of cell origin

RNA can carry genetic information and be used as catalysts (ribozymes). Lipids can self-organize

Ribozymes

a type of RNA that can be used as a catalyst

Primordial

what was thought to be last universal common ancestor

The Plasma Membrane

surrounds every cell and organelle, consists of lipids and membrane proteins

Glycoproteins

membrane proteins with polysacchrides attached to them

Extracellular matrix

• gives physical support to the cells

• animal cells have it made from collagen and proteoglycans

• ex. cartilage

Cytoskeleton

• made from 3D array of proteins

• gives the cell a distinctive shape and organization

• ex. microtubules, microfilaments, intermediate filaments

Nucleus envelope

composed of two lipid bilayers (double membrane)

Nucleolus

the most predominant structure in the nucleus

Nuclear pores

protein channels in the nuclear envelope that allow transport

Organlles

compartment of membranes with specific functions

Chloroplasts

converts solar energy into glucose (site of photosynthesis)

Mitochondria

site of aerobic respiration, wehre nutrients are converted to cellular energy in form of ATP (Kreb Cycle)

Endosymbiot Theory

theory that chloroplasts and mitochondria came from bacteria

1. resemble bacteria in size and shape

2. both have DNA

3. both have double membranes, the inner have bacterial type lipids

Ribosomes

• translates mRNA to proteinss

• not enclosed by a membrane

What organelle is not considered a true one

Ribosomes

A Virus

• consists of DNA or RNA, and is surrounded by a protein coat

• they are not cells, they are obligate intracellular parasites that are incapable of free-living

Adenovirus

consists of 36kb dsDNA genome packaged in proteins