Biochemistry Unit

Living cells are divided into two types:

Prokaryotic and Eukaryotic

Eukaryotic cells comprise...

all of the life kingdoms except monera

Eukaryotic cells can be easily distinguished through...

a membrane-bound nucleus

Eukaryotic cells also contain...

many internal membrane-bound structures called organelles

What do organelles do

They serve to perform metabolic functions and energy conversion. Other organelles like intracellular filaments provide structural support and cellular mobility.

An important member of the eukaryote family is

the plant cell

What are the 3 unique structures that set plant cells apart?

Plastids (organelle that contains pigment ex. chloroplast), cell walls, and vacuoles (central)

Prokaryotic cells are cells that...

lack a membrane-bound nucleus

Prokaryotic cells have few...

internal structures that are distinguishable under a microscope

Examples of prokaryotes:

Cells in the monera kingdom such as bacteria and cyanobacteria (also known as blue-green algae)

What are the 4 differences between Prokaryotic and Eukaryotic cells?

1) They don't have a membrane-bound nucleus and instead of having chromosomal DNA, their genetic information is in a circular loop called a plasmid

2) Bacterial cells are very small, roughly the size of an animal mitochondrian

3) Prokaryotic cells feature 3 major shapes: rod shaped (bacillus), sperical (coccus), and spiral (spirillus)

4) Instead of going through elaborate replication processes like eukaryotes, bacterial cells divide by binary fission and conjugation

Animal cell vs. Plant cell

Animal cells don't have a cell wall, central vacuole, and plastids

What are the 2 functions of the cell membrane

1) Barrier

2) Selective Transport

Barrier

- Prevents escape of matter needed to perform cellular functions

- Prevents entry of unwanted matter into cell

Selective Transport

There are two types: Passive and Active

Passive Transport describes...

the movement of substances down a concentration gradient and does not require energy use

What are the 3 types of Passive Transport?

1) Simple Diffusion: is the net movement of substances from an area of higher concentration to an area of lower concentration. This movement occurs as a result of the random and constant motion characteristic of all molecules, and is independent from the motion of other molecules.

2) Facilitated Diffusion: is the diffusion of solutes through protein channels in the plasma membrane

3. Osmosis: is the diffusion of water molecules down a water concentration gradient.

Active Transport is...

the movement of solute against a [gradient] and require the expenditure of energy, usually in the form of ATP. Active transport is achieved through 2 mechanisms.

What are Protein Pumps? (Mechanism in Active Transport - opposite of protein channel)

- Transport proteins in the plasma membrane transfer solutes such as small ion (Na+, K+, Cl-, H+), amino acids, and monosaccharides.

- The proteins involved with active transport are also known as ion pumps.

What is Vesicular Transport? (Mechanism in Active Transport)

Vesicles or other bodies in the cytoplasm move macromolecules or large particles across plasma membrane

What is exocytosis?

The process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell. This process is common when a cell produces substances for export.

What is endocytosis?

The capture of a substance outside the cell when the plasma membrane merges to engulf it. The substance subsequently enters the cytoplasm enclosed in a vesicle.

What is Phagocytosis/cellular eating (endocytosis)

Occurs when the dissolved materials enter the cell. The plasma membrane engulfs the solid material, forming a phagocytic vesicle.

What is Pinocytosis/ Cellular drinking (endocytosis)

Occurs when the plasma membrane fold inward to form a channel allowing disolved substances to enter the cell. When the channel is closed, the liquid is encircled within a pinocytic vesicle.

Phospholipids have a \_____ head and a \_____ tail.

hydrophilic, hydrophobic

What do phospholipid molecules form

a double or "bilayer

Hydrophilic (phospholipid)

"heads" face outwards, towards the watery environment that lies both inside (aka the cytoplasm)

Hydrophobic (phospholipid)

"tails" point inwards, towards each other.

Cholestrol is an example of...

a lipid which is a type of macromolecule

What does cholestrol act as

Patching substances to help the cell maintain an optimal level of fluidity

How many types of protein are involve with the cell membrane

2

What are integral membrane proteins?

These proteins are bound to the hydrophobic interior of the membrane

What are peripheral membrane proteins

These proteins are NOT bound to the the bilayer; instead they are bound to the integral membrane proteins

1. Transport (membrane protein function)

Many substances cannot freely diffuse through membranes. Instead, a specific compound may be able to cross a membrane by way of a hydrophilic protein channel. Alternatively, shape-shifting may allow some membrane proteins to shuttle molecules from one side of a membrane to the other.

2. Enzymatic Activity (membrane protein function)

Some membrane proteins, such as those associated with respiration and photosynthesis are enzymes.

3. Triggering Signal (membrane protein function)

Membrane proteins may bind to specific chemicals, such as hormones. Binding to these chemicals triggers changes on the inner surface of the membrane, starting a cascade of events within the cell.

Attachment and Recognition

Proteins that are exposed to both the internal and external membrane surfaces act as attachment points for a range of cytoskeleton elements, as well as components involved in cell-cell recognition, and bond to the extracellular matrix. For ex. Surface proteins can recognize elements of disease causing microbes that may try to invade cells, triggering an immune response.

Glycocalyx refers to...

the sugar chains

The glycocalyx can act as a...

lubricating layer and it can be attached to different components

When sugar chains are attached to proteins, what are they called?

Glycoproteins

Why do sugar chains bind to proteins

to serve as their binding sites

When sugar chains are attatched to lipids, what are they called?

Glycolipids

Function of Glycocalyx

Sites of intercellular communication

- receptors for peptide hormones and neurotransmitters are integral membrane proteins

Site of recognition by Immune System

- membrane proteins and carbohydrate groups (sugar chains) serve as identifiers of self and foreign.

Common elements carbon can bond to:

Oxygen, Nitrogen, Hydrogen

Bonds that are formed with common elements:

Polar bonds with O and N, Non-polar bonds with H and other C

Alkanes are hydrocarbons that are...

highly reduced and non polar \= do not form hydrogen bonds \= are hydrophobic

When is a carbon oxidized

If it undergoes a reaction wherein a new bond is formed with an atom of greater electronegativity than that which was before ("electron removal")

Oxidizing Agent

Substance that has a high tendency to gain electrons (reduced)

Reducing Agent

Substance that has a high tendency to lose electrond (most metals and hydrogen)

Hydroxyl

- Alcohol (as in ethanol)

- Polar, forms hydrogen bond, present in sugars and some amino acids

Carbonyl

- Aldehyde (as in formaldehyde)

- Polar, present in sugars

- Ketone (as in acetone)

- Polar, present in sugars

Carboxyl (acidic)

- Carboxylic acid (as in a acetic acid)

- Polar, acidic, present in fatty acids and amino acids

Amino (basic)

- Amine (as in tryptophan)

- Polar, basic, forms hydrogen bonds, present in amino acids

Sulfhydryl

- Thiol (as in ethanethiol)

- Forms disulfide bonds, present in some amino acids

Phosphate

- Organic Phosphate (as in phosphorylated molecules ex. ATP)

_ Polar, acidic, present in nucleotides and phospholipids

Build Legend

Carbon \= Black

Hydrogen \= White

Oxygen \= Red

Nitrogen \= Blue

Sulfur \= Yellow

Phosphorus \= Purple

Carbon is oxidized if it...

forms a single bond with oxygen

Anabolic reactions...

create linkages (endothermic) ex. dehydration synthesis (removal of water from portions of functional groups, and the formation of a linkage)

Catabolic reactions...

break linkages between functional groups (exothermic) ex. Hydration Decomposition (addition of water to a linkage to decompose a polymer. forming 2 functional groups)

Ether Linkages

Alcohol + Alcohol -dehydration synthesis\> Ether linkage + Water

- Most commonly found joining simple sugars into complex carbohydrates

Ester Linkages

Carboxylic acid + Alcohol -dehydration synthesis\> Ester linkage + water

- Esters join fatty acids &glycerol to form trigycerides.

- They also form phosphodiester bonds for DNA & RNA

Amide Linkages

Carboxylic acid + Amine -dehydration synthesis\> Amide Linkage + Water

- Amide linkages join Amino acids together to form polypeptides that eventually become proteins.

Carbohydrates contain...

carbon, hydrogen, and oxygen in this ratio (CH2O)n

What type of energy source are carbohydrates for biological systems?

primary

What are some examples of carbohydrates?

glucose, sucrose, cellulose, maltose, galactose ("ose" is the scientific suffix used for most carbohydrates)

What are monosaccharides?

- monomer (building block)

- single sugar units (ex. glucose, galactose, fructose)

What are disaccharides?

- two simple sugars joined by an ether linkage

- (ex. maltose \= glucose + glucose; sucrose \= glucose + fructose)

What are trisaccharides?

...etc., more than three are generally termed polysaccharides

Sugars contain the following functional groups...

- Hydroxyl (all - linear and cyclic)