Biology Exam 2

All cells have:

1. Plasma Membrane 2. Central location with genetic material 3. Cytoplasm

2 Classes of eukaryotes

1. Nucleus and Endomembrane 2. Energy-Related Organelles (Chloroplasts and Mitochondria)

Chloroplasts

2 Membranes (1st is outer for protection. 2nd has many folds and contains alpha and beta chlorophyl pigments). Makes carbohydrates from CO2 + H2O (Photosynthesis). One disc= thylakoid, stacks= Grana. Derived from Cyanobacteria. Fluid Substance= Stroma. Divide through Binary Fission.

Endosymbiosis Theory

2 bacteria came together and worked as one in a symbiotic relationship.

Mitochondria

2 membranes (1st is outer for protection. 2nd is folded and causes cristae). Makes Cellular respiration (Releases CO2). Uses carbohydrates in order to make more energy. Genome: mtDNA (can make up to 30 proteins). Derived from Purple Bacteria. Binary Fission. Generates heat with brown fat (used to regulate temperature). # of Mitochondria= Energy Demand of cell. Passed down maternally. Shape determines cell shape.

Nucleus

Houses genetic material. 2 Membranes (Outer is called nuclear envelope and inner overlap to make nuclear pores). Nuclear Pores: allow for passage ways between the nucleoplasm and the cytoplasm. The nucleolus is made of rRNA and ribosomes. RBC get rid of nucleus and cause short life span. mRNA leaves nucleus to go to cytoplasm to be translated to protein.

Chromosomes

Chromatin: Loose genetic material. Condensed genetic material is Chromosomes. 23 chromosomes. dipole because 23 pairs. Every cell has genome but it is expressed differently.

Endomembrane System

Nuclear Envelope, Rough Er, Smooth Er, Vesicles, Golgi, Plasma Membrane

Ribosomes

Not membrane bound. Made of rRNA and proteins. Site of protein synthesis. Could be attached to ER, by themselves or on a polyribosome (Strain of ribosomes attached by mRNA). Pancreas= A lot of ribosomes

Rough Endoplasmic Reticulum

Package and Sort Proteins. Have ribosomes. Glycosylation: Adding carbohydrates to lipids and proteins

Smooth Endoplasmic Reticulum

Site of lipid production. Storage of Calcium (Important for cell communication). Detoxification. Carbohydrate Metabolism

Golgi Apparatus

Transports and modifies lipids and proteins. Receives vesicles from ER on cis side, moves vesicles through median and releases them on the trans side. These vesicles can move out of the cell wall or become one with the cell wall.

Lysosomes

Membrane bound vesicle. Acidic environment important for destruction of material. Contains Lytic; Enzymes that digest cellular material. Autophagy: Recycling of cellular resources. Lysosomal Storage Diseases: Tay Sachs disease (cant break down lipids and causes death by 5).

Peroxisomes

Do not know how they originated. They have genetic material and can self replicate. Membrane bound vesicles that are important with detoxification. Lipid Metabolism. Catalyzes reactions that produce hydrogen peroxided. Changes hydrogen peroxide to water and oxygen. Toxic. Zellweger Syndrome: Little or no number of peroxisomes and cause death by 1.

Vacuoles

Membrane sacs for storage of water, nutrients and pigments. Causes Turgor Pressure- pressure between vacuole and the plant cell wall

Cytoskeleton

Helps keep the shape of the cell. Contains Actin Filaments, Intermediate Filaments and Microtubules

Actin Filaments

Smallest out of the three cytoskeleton types. Made of Globular proteins coming together to make fibrous strands (G actin and F actin). Used for helping microvilli. Cytoplasmic Streaming-Cell movement in amoeba and pseudopods.

Intermediate Filaments

Made of chains of polypeptides. Middle sized. Helps with nuclear envelope, cell-cell junction and cell structure.

Microtubules

Made of 2 Globular Proteins ( a and b tubulin). Pairs of tubulin make a dimer and 13 dimers spiral around to make a section of a microtubule. Component of the Microtubule Organization Center and the most important is the Centriole. Attached to movement proteins Kinesin and Dynein in order to move organelles.

Centrioles

Arranged in 27 microtubules with 9 pairs of 3. Found in the centrosome. Used in cell division. May give rise to basal bodies flagella and cilia. One centriole pair per animal cell.

Cilia and Flagella

Have the same 9+2 pattern of microtubules. Cilia are shorter than flagella. Cilia= Waves. Flagella= Propeller. Help in cell movement. Found in lungs and sperm.

Cell Membrane

1. Isolates Cell 2. Structure 3. Sensitivity 4. Defense 5.Chemical Reactions 6. Compartmentalization 7.Regulation 8. Communication. 70% of medications attach to the plasma membrane. Extracellular leaflet: Membrane that faces outside of cell. Cytosolic Leaflet: Membrane that faces inside the cell. Freeze fracture separates them. Proteins: Peripheral= located in cell. Integral= Transmembrane. Glycocaylx: Carbohydrate chain

Semifluid Membrane

Made of Phospholipids, Cholesterol (aid in cell communication), Proteins and Carbohydrates. 70%= Phospholipids and 20%= Cholesterol. In hot temp the membrane melts and in cold it cracks. When the temperature is hot then there are larger tails and less double bonded carbons. When it is cold there are shorter tails and more double bonded carbons. Psychrophilic= Likes cold. Mesophilic= Room temperatures. Thermophilic= Likes hot.

Phospholipids can more laterally and rotationally but not flipped. They can only be flipped using the enzyme flipase.

Membrane Proteins

Channel Proteins (Allow for direct flow), Carrier Protein (substance attaches to protein and it changes shape in order for it to respond to the message), Receptor Proteins (have a specific receptor and are used), Cell-Recognition Protein (have glycocalyx (chains of carbohydrates) and allows for your body to know which cells are yours and which cells are foreign). Enzymatic Proteins (found in bacterial cells and undergo chemical reactions).

Membrane Transport

Passive Transport (Diffusion, Osmosis and Facilitated Diffusion). Active Transport (Uses ATP, Active transport and Membrane-Assisted Transport).

High Permeability

Gases: o2, CO2 and N2. And very small polar molecules

Ethanol

Moderate Permeability

Water and Urea

Low Permeability

Large organic molecules (Glucose)

Very Low Permeability

Ions: Na+, Cl-, K+, Mg+

Very Large molecules: Amino acids, Polypeptides, Proteins and Nucleic Acids

Diffusion

Down the concentration gradient. Effected by: Distance, Gradient, Size of molecule, charge and temperature.

Ficks Law

Determines the rate of which gas diffuses into a membrane. Vgas (rate of diffusion)= (p1-p2) x A/T x D.

P1-P2= Concentration gradient

A= Surface Area (The larger the surface area the higher the Vgas)

T= Thickness of the membrane (Disproportional to Vgas)

D= How well the solute can dissolve in a solution (found in handbook)

In the lungs: Oxygen moves out into blood.

Osmosis

Movement of Solvent. Movement of water. Concentrated Solution: More solute than solvent. Dilute Solution: More solvent than solute

Osmotic Pressure

Determined by osmosis. When osmotic pressure is high, more water will flow into the cell. Colligative Property- Meaning it doesn’t matter what the solute is, just how much is there.

Regulated by blood pressure

Isotonic Solution

Same amount of solute to solvent.

Hypotonic Solution

Less solute than solvent so the water goes into the cell and can swell= Lysis

Hypertonic Solution

More solute than solvent so the water goes out of the cell and shrivels= Crenation

Plasmolysis

When a plant cell is put in a hypertonic solution and shrivels

Facilitated Diffusion

Across concentration gradient. Uses Carrier proteins and is specific. Tmax or Saturate is the maximum amount of particles that can diffuse into the cell because of the number of carrier proteins.

Active Transport

Requires ATP. Goes against concentration gradient. Main example is the Sodium Potassium Pump.

Sodium is high on the outside of cells. Potassium is high on the inside of cells. ATP looses a phosphate and turns into ADP and the carrier protein can move 3 sodium’s at a time and 2 potassium’s.

Primary and Secondary Active Transport: primary uses ATP directly and secondary relies on primary

Uniport= One substance. Co-Transport= 2 substances Symport= Moving in same direction. Antiport= Moving in opposite directions

Ex. Hydrogen Pump. Hydrogens are high on the outside of the cell

Functions of Electrochemical Gradients

Chemical gradient= sodium moving out of cell and potassium moving in

Electrical= Positives on outside trying to move into the negative inside of cells

This relationship (membrane potential) drives a cascade of energy in muscle and nerve cells. Nerves= -70 Muscles= -90

Membrane Assisted Transport

Exocytosis and Endocytosis

Exocytosis

Vesicle coming from endomembrane system and fusing with plasma membrane to secrete products outside the cell. Use of ATP. Ex. Neurotransmitters

Endocytosis

Vesicles moving product into the cell.

Phagocytosis (only some cells can do)- Moving solid particles into cell (cell eating). Called Phagosome

Pinocytosis(all cells can do)- Moving solute dissolved in water into the cell (cell drinking)

Receptor-Mediated- Like pinocytosis but with receptors and it wrapped in a coated pit (clathrin)

Tenacity

Ability of a solution to change cell shape by altering the movement of water. (swell/shrink)

Extracellular Matrix (ECM)

Made of Polysaccharides and Proteins. Helps to: Protect, Structural Support, Strength, Cell Signaling and Organization.

The ECM is secreted by the cell itself and the ECM can vary by the type of cell that is secreting it.

Proteins of the ECM

Adhesive and Structural Proteins

Integral Proteins

Bind to the plasma membrane. Are sticky and allow the cell to stick to the ECM. Contain region of fiber receptors for Fibronectin and Laminin to interact with carbohydrates and proteins.

Linking Proteins and Proteoglycans. Glycoaminoglycans (GAG’s)

Long unbranched polysaccharides usually highly negatively charged. Give the ECM a gel-like like consistency. Helps protect the cell membrane from tear. Important in areas like your joints. chondroitin sulfate, hyaluronic acid

Short amino acid chains

Job is to attach to water in order to resist compression in the ECM

Fibronectin and Laminin

Job is to bind the cell to the sugar layer

Structural Proteins

Contain fibers such as Collagen and Elastin. Anchoring is its main job. Ex. Anchoring muscle to muscle (ligaments) and muscle to bone (tendons).

Collagen

27 different types. Contains 3 polypeptide chains stuck together. Found in 75% of your skin and 45% of your body. Highly Structural

Elastin

Fibers made of proteins that are very stretchy and have recoil. As you grow older elastin starts to decrease which is bad for the persons blood pressure and respiration.

Membrane Junctions

3 different types of membrane junctions in animal cells.

Desmosomes (Anchoring or Adhesion) Junctions ,Tight Junctions and Gap Junctions

Desmosomes

Junction that contains plaques between the membrane of both cells. Has collagen fibers and filaments that run through the plaques to keep them in place. Intracellular filaments extend and connect between cells. Create a very tight junction and is seen skin cells and bladder wall. Very mechanically strong

Tight Junctions (Occluding)

Has proteins (Occludin and Claudin) that make barriers between cells. This makes materials go into the cells rather than in between them. Found in the blood brain barrier. Also found in the male body in the testis barrier- makes a barrier because sperm is haploid and the body would detect it as foreign material

Gap Junctions

All about the flow of signal. 6 connexons proteins coming together to form a channel. Found in the embryonic nervous system because as neurons developed you want them to be as connected as possible. Also seen in cardiac muscle.

Gap Junctions: Signaling Desmosomes: Anchoring

Plant Cell Walls

Made of cellulose. Have Middle Lamella (named Pectins)- made of polysaccharides and act like glue between the walls.

Contains Gap junctions called Plasmodesmata- allow the passage of water and ions.

Epithetical Tissue

Continuous sheets bind and has desmosome tissue. Found in skin cells and the gi-tract.

Connective Tissue

Used for support and connect tissues. Ex. In bones and cartilage. Contain ground substance. Blood is also a connective tissue and has fibers in its plasma that is used for blood clotting.

Nervous Tissue

Excitable membranes. Uses membrane action potential to generate activity in body. Used to control muscle cells. Generates electrical signals

Muscle Tissue

Excitable membranes. Facilitates movement. Generates electrical signals in order to stimulate muscle contraction.

Cell-Cell communication

Stimulus- Receptor- Control Center- Response

Types of Signaling

1. Direct 2. Contact-Dependent 3. Autocrine

Direct Signaling

Gap Junctions. Signal passes from the cytosol of one cell to the other

Contact-Dependent

Contact dependent needs the ligand to bind to a receptor. Membrane bound signals bind to receptors on neighboring cells.

Autocrine

Releases ligands that attach to its own receptors as well as neighboring cells. Ex. Phagocytes Antigens engulf foreign matter and place it on their cell membrane in order for T cells to come and bind to them so that the T cells can activate your immune system. Ex. Mitosis and the cell knows when it needs to stop dividing.

Paracrine Signaling

Its like Autocrine signaling but the signal that the cell releases only affects its neighboring cells. Ex. Neuron impulse and neurotransmitters being released.

Endocrine Signaling

Cell releasing signals that travel far and wide across the body to their target cell. Ex. Hormones

Cellular Response

Signal transduction: Mechanism in which cells share information

Stage 1

Receptor Activation: Ligand Binds to receptor

Stage 2

Signal Transduction

Stage 3

Cellular Response: Altered Metabolism, cell shape, gene expression etc.

Ligand Agonist

Ligand that enhances cellular activity

Ligand Antagonist

Ligand that blocks cellular activity

Binding between a ligand and receptor is usually…

noncovalent. And is reversible since ligands are released constantly to generate more of a response.

Types of Receptors

Intracellular Receptors and Cell Surface Receptors

Intracellular Receptors

Found in the cytoplasm or in the nucleus connected to DNA. Lipids, steroid hormones and other hydrophobic molecules can diffuse through the membrane. In plants: Auxins

Cell Surface Receptors

Ligand attaches to the receptor on the plasma membrane. Ligand gated ion channels. When the ligand binds then it opens up the gate. For example Acetylcholine will bind and open up the channel to allow Na+ to diffuse.

2.Influx of calcium opens up the channel of the neuron and allows the vesicle to bind to the plasma membrane.

High in nerve and muscle tissue because they make electrical signals.

Kinases

Enzymes that phosphorylate

Enzyme Linked Receptors

Have two components: Extracellular Domain and Catalytic Domain.

Enzymes Involved: Tyrosine, Serine, Threonine (All 3 accept phosphate groups)

Ex. Epidermal Growth Factor= Tyrosine-Kinase enzyme linked receptor. When the EGF attaches to the EGFR (receptor) then it causes mitosis and cell division in order to create scabs and stop bleeding. When the EGFR is activated at inappropriate times then it can cause cancer.

Phosphatases

Dephosphorylate. They remove a phosphate by a hydrolysis reaction and work opposite of kinases.

Gene Protein Couple Receptor (GPCRs)

Found in eukaryotes. Contains a heterotrimeric G protein with three different subunits (alpha, beta and delta). When signaling molecule binds to the receptor this causes GDP to change to GTP and activates the Alpha subunit. This causes a disconnection of the beta and delta subunits. This activation then activates the effector and creating a second messenger molecule.

cAMP second messenger molecule

When GDP is converted to GTP and activates the Alpha subunit, the effector is Adenylate Cyclase which turns GTP to cAMP. This is done by removing 2 phosphate groups (making it one phosphate, a ribose and a nucleic base). cAMP then activates a kinase which phosphorates and causes a signal.

Characteristics of 2nd Messengers

2nd Messengers are very short lived and they are the one that rely signals in the cell since the ligand cannot cross the membrane.

Phosphodiesterase (PDE)

Enzyme that breaks down cAMP to bring the signal to an end.

Caffeine stops the production of phosphodiesterase and causes cAMP to keep producing and signaling which leads to jitters.

DAG and IP3 second messengers

Another second messenger. GDP changed to GTP again and activates the effector Phospholipase. This then results in the activation of DAG (diacylglycerol) which is embedded in the plasma membrane since it is hydrophobic and DAG activates protein kinase C which does a cellular response. Phospholipase also activates IP3 which is able to diffuse into the cytosol since it is hydrophilic. IP3 goes to the smooth ER which causes the release of calcium. Calcium, IP3 and DAG then all act as messenger molecules and generate a cellular response.

Life has…

a constant flow of energy

Bioenergetics

The analysis of how energy powers the activities of living systems

Metabolism

All the chemical reactions in a living system

Energy

Promotes change and does work.

Energy Flows and nutrients cycle

Kinetic Energy

Energy of motion

Types: Mechanical, Light, Sound

Potential Energy

Stored Energy

Types: Chemical, Gravitational, Magnetic

Energy Flow

Sun-Producers-Consumers-Decomposers

Metabolic Heat

Energy that is given off as heat in a chemical reaction- mechanical energy

Laws of Thermodynamics

1. Conservation of Energy: Energy cannot be created or destroyed. Energy can be converted to one form or another. All the energy in the world is constant.

2. Law of Entropy (disorganization). Energy that is lost when it goes from one form to other.

Entropy Examples

Entropy is going to increase when disorganization increases. Ex. Breaking down a glucose molecule to hydrogens and oxygens is increasing entropy.

ex. The unequal distribution of hydrogen ions diffusing across the membrane is increased entropy.

Free Energy (Gibbs)

Amount of energy available in order to perform work.

H= G + TS

H- Enthalpy (change in heat content)

G- Gibs free energy

TS- Unusable energy. T (absolute temperature). S (entropy)

Exergonic Reactions

Reactions where the products have less usable energy than the reactants. (Spontaneous)

Delta G= Negative