Cell & Molec Exam 1

What do all cells have in common?

• Many cells can self replicate

• Similar molecules

• Genetic info is carried by DNA

What do all cells have in common?

Plasma membrane & cytoplasm

Cytoplasm

Materials inside the membrane

Plasma membrane

Outer covering

The Central Dogma of Molecular Biology

Everything a cell does is influences by the proteins a cell creates

What is the major difference between prokaryotes & eukaryotes?

Prokaryotes have no nucleus

Prokaryote characteristics

• Have a plasma membrane/cell wall

• Possess cytoplasm

• NO nucleus

• Most abundant & diverse cells, simplest, commonly called bacteria

What are the two prokaryotic domains?

Eubacteria & Archaea

Eubacteria characteristics

• Aka bacteria

• Small, usually single celled

• Some form clusters

• Use organic & inorganic food sources

• Found everywhere

Archaea characteristics

• Unique lipids in their cell membrane

• Live everywhere including “inhospitable” locations

• Not much know about them

Eukaryotic characteristics

• Larger and more complex than prokaryotic cells

• Contain a nucleus

• Important membrane-enclosed organelles

Nucleus

Eukaryotic cells store their DNA in a membrane covered structure, contains DNA

What surrounds the nucleus?

A lipid bilayer structure called the nuclear envelope with nuclear pores

When are chromosomes visible?

Only when the cell is dividing, most of the time DNA is decondensed and too long to fit inside the nucleus

What organelle generates ATP?

Mitochondria

What is the basic chemical fuel that powers most of the cell’s activity?

ATP, another energetic molecule is GTP

What does the endosymbiotic theory focus on?

The origin of mitochondria

What do chloroplasts do?

Capture energy from sunlight to generate usable energy

Chloroplast reaction

• Absorbs photons from light

• Produces high energy sugars

• The by-product/metabolite is O2

What does the Endoplasmic Reticulum do?

Protein folding, protein synthesis (parts that contain ribosomes)

What does the Golgi Apparatus do?

• Packages things for specific destinations

• Any protein destined for the plasma membrane or that is destined to be released from the cell, comes here for modifications

What do lysosomes do?

Internal digestion of old and unwanted material, recycle

What are vesicles?

• Transport vesicles, carry materials between one membrane enclosed organelle to another

• “Lipid droplets with stuff inside of them”

• Continuous exchange of materials occurs between the ER, Golgi, Lysosomes, and the outside of the cell

Exocytosis

Export out of cell

Endocytosis

Import into cell

What is cytoplasm?

• An aqueous environment surrounding organelles

• Site of many chemical reactions fundamental to cells existence

  • Protein synthesis by ribosomes

Involved in cellular movement, controls the shape of the cell

Actin

During cell division they separate cellular contents

Microtubules

Involved in mechanical strength

Intermediate fibers/filaments

3 Protein filaments in Cytoplasm

• Actin

• Microtubules

• Intermediate fibers/filaments

What are motor proteins?

They consume energy (ATP) to move along the filament tracks, carrying: organelles, proteins, or vesicles

Structures in plant cells that are not usually found in animal cells

• Cell wall - cellulose

• Chloroplasts

• Vacuole - fluid filled sac to maintain water balance

4 Small Organic Molecules

• Simple sugars

• Fatty acids

• Amino acids

• Nucleotides

Simple sugar macromolecule

Starch

Fatty acids macromolecule

Fats and lipids

Amino acids macromolecule

Proteins

Nucleotides macromolecule

Nucleic acids (DNA/RNA)

Features of chemical bonds

• Transfer of electron (gain or loss)

• Generation of cation or anion

• Opposite charges attract

• Store energy

3 types of chemical bonds

• Ionic

• Covalent

• Non-covalent

Ionic Bonds

Involves transfer of electrons from one atom to another, they are 10-100 times weaker in an aqueous solution than covalent bonds

Cation (ionic bonds)

Positively charged

Anion (ionic bonds)

Negatively charged

Covalent Bonds

• Involve sharing electrons between atoms

• “Transient interactions”

• Example - hydrogen bonds

What type of bonds hold H2O together?

Covalent, aka they share electrons but not equally

H2O charges

• The O has a partial negative charge

• The H would have partial positive charges

Hydrogen Bonding

Hydrogen bonding between water molecules is responsible for the many unique properties of water

What type of bond holds DNA together?

Hydrogen bonding

Covalent bond strength

Strongest

Ionic bond strength

Moderate

Hydrogen bond strength

Weakest

Polar molecules in water can form acids or bases

AKA covalent bonds with hydrogen atoms with strong partial charge

What do acids do?

• Release protons (H+) when dissolved in water

• Cause more H+ to be released into H2O = H3O

What do bases do?

• Accept protons (H+) when dissolved in water

• Remove an H+ from H2O = OH-

What is the pH scale?

The H+ concentration is expressed using a logarithmic scale

As pH increases…

Less acidic

As pH decreases…

More acidic

What are Buffers?

• They resist changes in pH

• Chemical reactions only work at specific pH levels

What kind of bonds are simple sugar monomers held together by?

Covalent bonds, to form longer chains

Condensation reaction

• Forms bonds

• Byproduct is water

• Energetically unfavorable

Hydrolysis reaction

• Breaks down bonds of monosaccharides

• Utilizes water

• Energetically favorable

How do animal cells store glucose?

As glycogen

How do plant cells store glucose?

As starch

What is chitin?

Insect exoskeleton, fungal cell walls

What are plant cell walls made of?

Sugars, cellulose

3 Properties of Fatty Acids

• Saturated tail

• Unsaturated tail

• Ester bonds

Saturated tail characteristics

• Has no double bonds

• Straight

Unsaturated tail characteristics

• Has one or more double bonds

• Kinked

What type of bonds are ester bonds?

Covalent

Cell Membrane contains Fatty Acids

• Fatty Acid

  • Hydrocarbon chain

  • Hydrophobic

• Carboxyl Group

  • Hydrophilic

• Tightness of tails affects membrane fluidity

Lipids are __ in water, but __ in fat & organic solvents

Insoluble, soluble

True or False - lipid subunits are not directly linked together

True

Kinks in fatty acids

• The kinks are created by the double bonds interfere with the molecules packing ability

• The absence or presence of double bonds is the difference between hard and soft margarine

What do all amino acids possess?

Carboxyl and Amino Groups

What distinguishes amino acids from each other?

The side chain (R) distinguishes amino acids from one another

How many different amino acids are there?

20

What is a chain of amino acids called?

Polypeptide

How are amino acids linked?

Peptide bonds (covalent)

Primary Structure

• Range from 30 to 10,000 amino acids

• Most are 50 to 2000 in length

Secondary Structure

Polypeptide chains may form alpha helices or beta pleated sheets

Intraprotein Hydrogen Bonding

Stabilizes the protein’s structure

Backbone-to-backbone

Hydrogen bonding between peptide bonds

Backbone-to-sidechains

Hydrogen bonding between a peptide bond and an amino acid side chain

Side chain-to-side chain

Hydrogen bonding between 2 amino acid side chains

Types of protein shapes

• Globular

• Fibrous

• Form filaments, sheets, rings, or spheres

Shape of protein is specified by what?

Amino acid sequence

What kind of interactions help proteins fold and stay folded?

Noncovalent

Quaternary Structure

• Subunits - a protein within a protein

• Dimer

  • Same - homo

  • Different - hetero

• Tetramer

• Non-covalent interactions

Hemoglobin

• 4 subunits

• 4 globins - 4 subunits combine to form 1 hemoglobin

Nucleotides

Nitrogen-containing ring (base) linked to 5-carbon sugar with phosphate group attached

Sugar can be

• Ribose (form RNA)

• Deoxyribose (form DNA)

Phosphodiester Bonds

• Hold nucleotides together

• Covalent bonds

What gives a nucleotide its name?

Base

Metabolism

Sum of all chemical reactions required for life

Catabolism

Breakdown - created energy for later use

Anabolism

Uses energy to make new molecules

1st law of Thermodynamics

Energy cannot be created or destroyed, it can be converted

2nd Law of Thermodynamics

• The drive of energy to go from unstable form to more stable form

• Messy and disordered is more stable than compared to ordered

Potential Energy

• Stored Energy

• Ex. stationary hamster on a wheel

Kinetic Energy

• Energy that is created because of motion

• Ex. once a hamster is running on a wheel

What is entropy?

Measure of a systems disorder