biol140 exam 2

what are carbohydrates monomers and polymers?

Monosaccharides are carbohydrates monomers and polysaccharides are carbohydrates polymers

Bonds that form carbohydrates

a carbonyl group (C=O), hydroxyl groups (-OH), and many carbon-hydrogen bonds (C-H)

disaccharide

Two sugars linked together

glycosidic linkage

When sugars are linked when a condensation reaction occurs between 2 hydroxyl groups and a covalent bond. Glycosidic bonds: covalent bonds that link monosaccharides together

Simple carbohydrates

fit Cn(H2O)n formula exactly

Complex carbohydrates

slightly differ from Cn(H2O)n and can also have P, N or S atoms.

Hydrolysis

break down polysaccharides into individual monosaccharides.

an alpha 1,4 glycosidic linkage vs a beta 1, 4 linkage.

Both linkages are between C-1 and C-4 carbons but C-1 hydroxyl groups are on opposite sides of the plane. The beta linkage is on top while alpha is under.

2 main functions of Carbohydrates

Structural support: used to build structures (build plant cell walls like cellulose, chitin) Energy - storage: used for short-term energy storage (starch and glycogen)

Where do plants store sugar

Plants store sugar as starch: it is composed of alpha glucose monomers (forms helix)

amylose

are unbranched starch with only alpha 1, 4 glycosidic linkages

amylopectin

branched starch with some alpha1,6 glycosidic linkages

Where do animals store sugar

Animals store sugar as glycogen: stored in liver and muscle cells, can be broken into glucose monomers for energy, highly branched alpha glucose polymers and nearly identical to starch

Two structural polymer for polysaccharides

Cellulose and chitin

Cellulose

a structural polymer: major components of the protective cells called the cell wall, made of beta-glucose monomers joined by beta-1, 4 glycosidic linkages, every other glucose is flipped so it generates a linear molecule rather than helix and permits hydrogen bonds to form between adjacent parallel strands.

Chitin

structural polymer found in cell walls of fungi and exoskeletons of insects: monomer is N-acetylglucosamine (NAG) and structure is similar to cellulose

Peptidoglycan

structural polymer found in bacterial cell walls

role of carbohydrates in cell identity

Carbohydrates indicate cell identity, Display information on the outer surface of cells: Glycoproteins - proteins with attached carbohydrates and glycolipids - lipids with attached carbohydrates, Glycoproteins and glycolipids are key molecules in: Cell–cell recognition: Identify cells as “self” and Cell–cell signaling: Communication between cells, In photosynthesis, plants harvest energy from sunlight and store it in the bonds of carbohydrates.

Where is potential energy stored

in the Bonds of Molecules like carbon dioxide and carbohydrate.

What is the plasma membrane

Serves as selective barrier: allows entry of materials needed by cell and keeps damaging materials out of cell. Facilitates chemical reactions necessary for life: allows chemical reactions to occur by sequestering appropriate chemicals

What are lipids

Carbon-containing compounds insoluble in water and insolubility due to high proportion of nonpolar (c-c) and (c-h) bonds

what are isoprenoids

a hydrocarbon chain, function as pigments, scents, vitamins, and hormone precursors, building blocks for more complex lipids

What are fatty acids

Simple lipid made of hydrocarbon chain bonded to polar carboxyl functional group. They are a hydrocarbon chain bonded to a carboxyl (-COOH) functional group: Contain 14–20 carbon atoms and can be saturated or unsaturated.

Saturated hydrocarbons chains

consist of only single bonds between carbons, has maximum number of hydrogen atoms

Unsaturated hydrocarbon chains

have one or more double bonds in hydrocarbon chains: hydrogen atoms are removed to make double bond, Forms “kink” in chain, Polyunsaturated chains have many double bonds

How Does Bond Saturation Affect Hydrocarbon Structure?

Saturation changes physical state: foods that contain lipids with double bonds said to be healthier.

What are the 4 kinds of lipids

Fats, Phospholipids, Steroids, waxes

What are steroids

Family of lipids, distinguished by bulky, four-ring structure, differ from one another by functional groups attached to carbons in rings

Examples: Hormones estrogen and testosterone, cholesterol - component of plasma membranes

what are fats composed of?

three fatty acids linked to glycerol (also called triacylglycerols or triglycerides)

What is the primary role of fats?

energy storage: Large number of high-energy bonds in fatty acid chains and Bonds allow fats to store twice as much chemical energy

How do fats form?

by dehydration reactions between: Hydroxyl group of glycerol and Carboxyl group of a free fatty acid

Glycerol and fatty acid molecules become joined by

ester linkage

what do Phospholipids consist of

glycerol linked to phosphate group and two hydrocarbon chains, with fatty acid tails

what is the primary role of phospholipids

to form cell membranes

How do phospholipids interact with water?

Hydrophilic “head” region contains: Glycerol, Negatively charged phosphate group, Charged or polar group. Hydrocarbon “tail”: Nonpolar and hydrophobic, Water molecules cannot form hydrogen bonds with tail so they interact with the heads

what is ampiphatic

Substances with both hydrophilic and hydrophobic regions.

Amphipathic lipids can form _________ which are created when lipid molecules align in paired sheets

lipid bilayers

What is selective permeability

the property of a cell membrane that allows certain molecules to pass through while blocking others

Which molecules can move across phospholipid bilayers quickly and which don’t?

Small or nonpolar molecules move across phospholipid bilayers quickly, charged or large polar substances cross slowly, if at all

How does lipid structure affect membrane permeability?

Length of hydrocarbon tails, Saturation of state of hydrocarbon tails, presence of cholesterol molecules.

What affects the behavior of membrane

degree of saturation and length of tails

How does unsaturated bonds affect membrane permeability

Double bonds in hydrocarbon tails can cause “kink” in hydrocarbon chain, hold hydrophobic tails together, weakens barrier to solutes

How does saturated bonds affect membrane permeability

saturated hydrocarbon tails have fewer spaces and stronger hydrophobic interactions: Makes membranes even denser, Hydrophobic interactions become stronger as saturated hydrocarbon tails increase in length, membranes containing phospholipids with longer tails

How does adding cholesterol affect membrane permeability

Adding cholesterol to membranes increases density of hydrophobic section, Cholesterol reduces membrane permeability and bulky cholesterol rings force phospholipid tails closer: Increasing their packing density

What are the function of lipids

Store chemical energy, Act as pigments that capture/respond to sunlight, Serve as signals between cells, form waterproof coatings on skin and cells, Act as vitamins in cellular processes

what is a vesicle

a small, membrane-bound sac within a cell that functions to transport materials inside the cell. Vesicles are crucial for moving substances within the cell. Can form from phospholipids

what are liposomes

Small bubble-like structures surrounded by phospholipids and artificial membrane-bound vesicles

How Does Temperature Affect the Fluidity and Permeability of Membranes?

Phospholipids in plasma membranes move laterally within bilayer and membrane fluidity decreases as temperature drops: Molecules in bilayer move more slowly, Hydrophobic tails pack together more tightly, Decreased membrane fluidity causes decreased permeability

what is Diffusion

Spontaneous movement of molecule and ions: Concentration gradient created by difference in solute concentrations and net movement from high-concentration regions to low-concentration regions. It increases entropy.

When does equilibrium occur in diffusion

when molecules or ions are randomly distributed throughout solution: Molecules are still moving randomly but there is no more net movement

when does passive transport occur?

occurs when substances diffuse across membrane in absence of an outside energy source

What is Osmosis

Special case of diffusion, water moves quickly across lipid bilayers and only occurs across selectively permeable membranes. Water moves from regions of low solute concentration to regions of high solute concentration: Dilutes higher concentration of solute and equalizes concentration on both sides of bilayer.

Hypertonic

Outside solution with higher concentration than inside of the cell, water will move out of the cell and the cell will shrink.

Hypotonic

solution with lower concentration than inside of cell, water will move into the cell and cell will swell

isotonic

If solute concentrations are equal on outside and inside of cell, no net water movement and cell size remains the same

What are protocells?

Simple vesicle-like structures that harbor nucleic acids, Possible intermediates in evolution of cell

Fluid-mosaic model of membrane structure suggests

Some proteins span membrane instead of being found only outside lipid bilayer and makes membrane fluid, dynamic mosaic of phospholipids and proteins

What are the two main types of membrane proteins

Integral and Peripheral membrane proteins

Integral membrane proteins

integrated within the cell membrane usually spanning the entire bilayer

Peripheral membrane proteins

proteins on the periphery (or perimeter) of a cell membrane (horizontal)

How can membrane proteins be separated from membrane

with detergents: small amphipathic molecules that can form micelles and unlike amphipathic lipids, detergents are water soluble. Allowed identification of membrane proteins that affect permeability: Channels, Carriers, Pumps

what are ion channels

They are specialized transmembrane proteins, form pores, or openings, in membrane, Allow ions to cross membranes.

when do electrochemical gradients occur

when ions build up on one side of plasma membrane: Establish both concentration gradient and charge gradient and Ions diffuse down their electrochemical gradients

Aquaporins

Permit water to cross plasma membrane

gated membrane channels

Open or close in response to signal such as binding of particular molecule or change in electrical voltage across membrane. Movement of substances through channel proteins is passive meaning it does not require energy and Ions and small polar molecules diffuse across lipid bilayer.

What is cystic fibrosis

It affects cells that produce mucus, sweat, and digestive juices, Secretions become abnormally concentrated—clog pathways, caused by defects in transmembrane protein CFTR which allows passage of chloride ions. Defective CFTR prevents chloride ions from leaving cell surrounding airway passage

What are carrier proteins

Carrier proteins selectively pick up solute on one side of membrane and drop it on the other side. Facilitated diffusion can also occur through specialized membrane proteins, mechanism of transport differs from channel proteins (best studied carrier protein is glucose)

Facilitated diffusion through channels or carriers is

passive transport because it moves substances with their concentration gradient and does not require input of energy

Active transport

Moves substances against their gradient, Requires input of energy, ATP often provides energy in cells: Phosphate group transferred via active transport protein (“pump”)

The Sodium–Potassium Pump

Uses ATP, Transports Na+ and K+ ions against their concentration gradient

function of plasma membrane

selective permeability to maintain intracellular environment

Cell theory states that call organisms consist of cells and all cells have

Proteins (perform most of the cell’s functions), Nucleic acids (store, transmit, and process information), carbohydrates (provide chemical energy, carbon,support, and identity), plasma membrane (serves as a selectively permeable membrane barrier)

Cells are divided into two fundamental types based on morphology:

1. Eukaryotes have membrane-bound nucleus

2. Prokaryotes lack membrane-bound nucleus

organisms are divided into three domains:

Bacteria (prokaryotic), Archaea (prokaryotic), Eukarya (eukaryotic)

what do prokaryotic cells contain?

cell membrane, cytoplasm, ribosomes, nucleoid, cell wall, chromosomal dna, and plasmids

how do phospholipid components differ in bacteria vs archaeal?

Bacterial phospholipids consist of fatty acids bound to glycerol and Archaeal phospholipids used branched isoprenoid chains bound to glycerol

what is the cytoplasm

All contents of cell inside membrane

what is the chromosome in prokarytoic cells?

Most prominent structure inside prokaryotic cell, most bacterial and archaeal species have single, circular chromosome: Consists of large DNA molecule associated with proteins, DNA molecule contains information, Proteins give DNA structural support

what are plasmids

circular, supercoiled DNA molecules in prokaryotic cells

what are ribosomes in prokaryotes

Macromolecular machines, have large and small subunit, consist of RNA molecules and protein, used for protein synthesis, Ribosomes in bacteria and archaea similar in size and function: Primary structure of RNA and protein components different

Cytoskeleton in prokaryotic

long, thin protein filaments in cytoplasm, in bacteria cytoskeleton essential for cell division, maintains cell shape

internal photosynthetic membranes

are specialized membrane systems within chloroplasts where the light-dependent reactions of photosynthesis occur, converting light energy into chemical energy. They develop as infoldings of plasma membrane contain enzymes and pigment molecules required for reactions to occur

organelles in bacteria are

Membrane-bound compartments, Perform specialized tasks: store calcium ions, hold magnetite crystals to serve as a compass, concentrate enzymes for building organic compound

What is the cell wall in prokaryotes

composed of tough, fibrous layer, Surrounds plasma membrane, Protects shape and rigidity of cell. In bacteria: Primary structural component of cell wall is polysaccharide peptidoglycan and some have outer membrane made of glycolipids

Structures found on bacterial surfaces

flagella and fimbriae

What are Eukaryotic flagella

Short, hairlike projections found in some eukaryotic cells, 9 microtubule pairs (doublets). Biologists have concluded that prokaryotic and eukaryotic flagella evolved independently even though purposes are similar

what are Flagella

hair-like appendages that help certain cells move

what are fimbriae

needle like projections that promote attachment to other cells or surfaces

eukaryotes can be

multicellular or unicellular

benefits of organelles

Organelles compartmentalize volume inside eukaryotic cells into small bins: Fluid portion of cell, cytosol, has small volume and offsets effects of low cell surface-area-to-volume ratio.

2 of benefits of compartmentalization

Separation of incompatible chemical reactions and increasing efficiency of chemical reactions

components of eukaryotic cells

nucleus, cytoplasm, cell membrane, mitochondria, endoplasmic reticulum (ER), golgi appparatus, lysosomes, ribosomes

what is nucleus in eukaryotic cells

Information center of eukaryotic cells, genetic info in dna is decoded and processed, large suites of enzymes interact to produce RNA messages. Large, highly organized membrane bound compartment

what is the nuclear envelope

surrounds the nucleus, studded with pore-like openings, separates nucleus from rest of cell, connects inside of nucleus with cytosol, and consists of about 30 different proteins.

what is the nuclear lamina

part of the nuclear envelope, are intermediate filaments: Make up nuclear lamina layer, defines shape of nucleus—stabilizes envelope, Form a dense mesh under nuclear envelope, Anchor chromosomes and Lattice-like sheet of fibrous protein

what is the nucleolus

Location where ribosomal RNA is synthesized and ribosome subunits are assembled, in nucleus

what are ribosomes

are complex molecular machines that manufacture proteins: Lack membrane and not considered organelles. Some ribosomes are free in the cytosol: Manufacture proteins that remain in cytosol or are imported to other organelles (e.g., nucleus). Some are attached to endoplasmic reticulum: Manufacture proteins with other fates.

what is the Endoplasmic reticulum

a part of a transportation system of the eukaryotic cell, and has many other important functions such as protein folding

Rough endoplasmic reticulum (rough ER)

Studded with ribosomes (Dark, knobby looking structures), Synthesizes proteins that will be: shipped to another organelle, inserted into plasma membrane, secreted to the cell exterior