MCB 150 Exam 1

kms

nucleoid

not surrounded by a membrane, usually one chromosome

eukaryotic cell

animal cell

The 3 domains of life are?

Bacteria, Archaea, Eukarya

Cell theory

Cells are the fundamental units of life, all organisms are composed of one or more cells, and all cells arise from pre-existing cells.

some cells(plants and most prokaryotes have a relatively________ providing shape and protection

rigid cell wall

every cell is surrounded by plasma membrane

that controls the movement of substances in and out. It is selectively permeable. is an interface for cells where information is received from adjacent cells and extracellular signals.

4 major types of biological polymers (macromolecules )

Carbohydrates(polysaccharides) [sugars], lipids [fats], proteins, nucleic acids.

macromolecules (polymers) are made up of monomers

Proteins, Nucleic Acids, Polysaccharides, (membrane) lipids

proteins are composed of

amino acids linked by peptide bonds.

nucleic acids are composed of

nucleotides linked by phosphodiester bonds.

polysaccharides are composed of

monosaccharides linked by glycosidic bonds.

(membrane) Lipids are composed of

fatty acids and usually glycerol.

condensation (dehydration synthesis)

monomer, in water out.

hydrolysis

water in, monomer out

Macromolecules (carbohydrates)

large molecules made up of sugar units, serving as energy sources and structural components in cells, or insects such as exoskeletons.

General formula of a carbohydrate

(H2O)n, where n is the number of carbon atoms. a 1:2:1 ratio.

Monosaccharides are typically found with

3, 5, or 6 carbons

Archea

single-celled organisms that are distinct from bacteria and eukaryotes, often found in extreme environments. closer realted to us than prokaryotes

Every cell is surrounded by a

plasma membrane that regulates entry and exit of substances. cell membrane.

plasma membrane

Allows cells to maintain a constant internal environment
- Acts as a selectively permeable barrier
- Is an interface for cells where information is received from adjacent
cells and extracellular signals
- Has molecules that are responsible for binding and adhering to
adjacent cells

Some monosaccharides have identical formulas but
different structures

isomers

Two monosaccharides can be brought together to form a very
simple polysaccharide called a

disaccharide. It consists of two monosaccharides linked by a glycosidic bond.

The chemical formula for a disaccharide
of hexose sugars is

C12H22O11

One monomer is a

monosaccharide

Two monomers are a

disaccharide

Several monomers are called an

oligosaccharide (oligo=several)

Hundreds or thousands of monomers are a

polysaccharide (poly=many)

Carbohydrates can be modified

by adding functional groups or altering their structure. Linkage of oligosaccharides to other macromolecules
- When covalently linked to membrane proteins or lipids, carbohydrates act as identification and recognition molecules (chemical markers), as in blood typing.

Polysaccharides serve as chemical sources of energy
Polysaccharides serve as chemical sources of energy

or structural compounds

• Cellulose

• Starches

• Glycogen

Cellulose

The most abundant carbon-containing (i.e., organic) compound on
Earth

Cellulose

found in plant cell walls

Cellulose

Linear, unbranched polymer of glucose
- monomers covalently linked by β-1,4 glycosidic linkages
- linear polymers held together by hydrogen bonding with
neighboring strands

Starches

Found chiefly in seeds, fruits, tubers, roots and stems of plants;
energy storage

Starches

Helical, unbranched or loosely branched polymers of glucose
- monomers within chains covalently linked by α-1,4 glycosidic
linkages
- chains branch by connecting with other chains by α-1,6 glycosidic
linkages

Glycogen

Found in muscle and liver cells of animals; energy storage

glycogen

Helical, highly branched polymers of glucose
- monomers within chains covalently linked by α-1,4
glycosidic linkages
- chains branch by connecting with other chains by α-1,6
glycosidic linkages

Lipids

Defined by a physical property, not a chemical structure
• Vary widely in structure

Energy Storage

Triglycerides

Biomembrane Composition

Phospholipids & Glycolipids form the structural basis of cell membranes, providing a barrier and enabling compartmentalization.

Chemical Signaling

Steroids

The monomers of (biological membrane) lipids

are fatty acids and glycerol, which combine to form various lipid structures essential for membrane integrity.

3 Fatty Acids + Glycerol =

Triglyceride

2 Fatty Acids + Glycerol + Phosphate =

Phospholipid

Phospholipids are (hydrophobic and hydrophilic)

amphipathic molecules that form biological membranes, with hydrophobic tails and hydrophilic heads.

Phospholipids in water will spontaneously form

micelles or bilayers that create a barrier between the inside and outside of cells.

Bilayers have exposed edges, and will fold into

vesicles to minimize exposure to water. (liposomes)

Some membrane lipids are

glycolipids or cholesterol, which contribute to membrane structure and function.

The fourth type of lipids are

Steroids

Steroids

Can be used as circulating hormones like estrogen and
testosterone, or as membrane components

Animal cells have ________ in their biomembranes

cholesterol for fluidity and stability.

Biomembranes are (shape)

Asymmetrical

Membrane-associated proteins

are proteins that are attached to or associated with cell membranes, playing key roles in signaling, transport, and maintaining cell structure.

Lipid-linked proteins

Are attached to the membrane via lipid tails, which anchor them to the lipid bilayer.

Peripheral proteins

are loosely attached to the membrane surface and can be removed without disrupting the membrane structure.

Transmembrane proteins

Span the entire membrane, with regions exposed to the cell's interior and exterior. They facilitate the transport of substances across the membrane.

proteins serve a variety of functions

Transport, Enzymatic activity, Signal transduction, Cell-cell recognition, Intercellular joining, Attachment to, the cytoskeleton
and extracellular, matrix (ECM) for support.

Biomembranes are

selectively permeable barriers that separate cellular compartments and regulate the movement of substances.

does it go through?

small polar molecules can pass through easily, while larger or charged molecules require specific transport mechanisms.

Biological membranes are (shape)

fluid

If biomembranes are fluid, in what ways can the lipids
move around within the membrane?

They can move laterally, rotate, or flex their tails.

Membrane fluidity is temperature-dependents

and can be affected by the presence of unsaturated fatty acids and cholesterol.

_________ fats take up less space and are closer packed together

Saturated

fluidity and stability in phospholipid membranes have a _____ relationship

inverse

Nucleic Acid

Deoxyribonucleic Acid (DNA) and Ribonucleic
Acid (RNA) are the two main types of nucleic acids, essential for storing and transmitting genetic information.

The monomers of Nucleic Acids are

nucleotides, which consist of a sugar, phosphate group, and nitrogenous base.

Numbering, labeling, and naming conventions:
Base + Sugar =

Nucleoside

Nucleoside + 1 Phosphate

nucleoside monophosphate

Nucleoside + 2 Phosphates

nucleoside diphosphate

Nucleoside + 3 Phosphates

nucleoside triphosphate

Pyrimidines

a class of nucleobases that includes cytosine, thymine, and uracil, characterized by a single six-membered ring structure.

Purines

a class of nucleobases that includes adenine and guanine, characterized by a two-ring structure.

The nucleotides (abbr. nts) of DNA and RNA differ in two
important ways:

DNA contains deoxyribose, while RNA contains ribose, DNA uses thymine (T) as one of its four nitrogenous bases, whereas RNA uses uracil (U) instead of thymine

Biomembranes have associated proteins,

Membrane-associated, Transmembrane proteins, Peripheral proteins, Lipid-linked proteins

In ________ inhibition, the inhibitor molecule binds

to the enzyme in a place other than the active site

noncompetitive

In _______ inhibition, the inhibitor molecule physically

resembles the natural substrate, and occupies active site

competitive

Irreversible Inhibitors

molecules that permanently bind to an enzyme, preventing its activity.

_______ inhibition is a demonstration of the

important point that enzymes must ultimately be

unchanged if they are to be used over and over

Irreversible

Most tend to be near body temperature and Ph?

(37 °C) and neutralpH (7.0)

positive Gibbs free energy

endergonic

negative Gibbs free energy

exergonic

Enzymes will most likely cause some conformational

change in the substrate molecule(s), but they themselves

usually change shape upon binding substrate

Called induced fit and return to normal afterwardsafter the reaction is complete.

Enzymes bind substrates with extremely high specificity

into their

active sites, facilitating biochemical reactions.

___ = activation energy, which converts substrates into unstable transition states

Ea

2 different meanings for the word spontaneous

1. Typical meaning: happens automatically.

2. Biology meaning: a reaction that releases energy, much of

   which is lost as heat

Reactions that require energy are called

biosynthetic or anabolic

Reactions that release energy are called

catabolic or also referred to as spontaneous reactions.

Many proteins are _____: biological catalysts; they

facilitate biological reactions

enzymes

If denaturing agent is removed

some proteins will resume properly folded 3D structure

instructions” are in ______ structure

the primary 1*

Removal or inactivation of stabilizing forces unfolds

(_____) the protein to 1° structure, but no peptide

bonds are broken

denaturing

if a protein is denatured

All 2° and 3° structure is lost

Disulfide linkages →

Covalent

Relative stabilities of biomolecular forces:

Disulfide linkages → Covalent

• Ionic bonds → Easily made and broken

• Hydrogen bonds

• Hydrophobic clusters

• Van der Waals forces

Quaternary Structure (4°)

Found in proteins with multiple polypeptide chains (subunits)

Subunits can be same or different(for quaternary structure 4*)

- 2 identical subunits = homodimer

- 2 different subunits = heterodimer

Tertiary Structure (3°):

Unique 3D folded structure

• Final conformation of some proteins

• Due to interactions between R-groups with each other and

with backbone

tertiary structure is Stabilized by:

- H-bonds between polar (or charged) side chains

- H-bonds between hydrophilic side chains and backbone

- Ionic bonds between acidic and basic amino acids

- Hydrophobic clustering of non-polar side chains

- Van der Waals forces

- Disulfide linkages

Prions

Infectious agents composed of misfolded proteins that can induce abnormal folding of normal proteins.

________ the only part that differs—is what

makes one amino acid different from another

The R group

________ is a covalent chemical bond that links two amino acids together, forming the backbone of proteins

peptide bond