bio exam 2

explain the relationship between cell function and cell size

smaller cells have higher surface area to volume ration which allows more efficient exchange of materials. large cells have less surface area relative to volume.

List the principles of The Cell Theory

1. all organisms are made of cells

2. cells are the basic unit of life

3. all cells come from pre-existing cells

Describe the basics of two types of light microscopes and two types of electron microscopes and the use of each

bright-field: uses light and often stains cells

fluorescence: uses fluorescent dyes to identify structures

scanning (SEM): shows 3-D surface structures

TEM: shows internal structures

Describe how magnification, contrast, and resolution relate to microscopy

magnification makes an image larger

contrast makes the specimen stand out

resolution is the ability to distinguish two close objects as separate

Name the parts of the plasma membrane

phospholipid bilayer

proteins

cholesterol

carbohydrates

Describe the function of the plasma membrane

forms a selectively permeable boundary that controls what enters and leaves the cell and allows cell signaling

Identify the key structures of the bacterial cell and their functions

cell wall = support

plasma membrane = transport

nucleoid = DNA

ribosomes = proteins

capsule = protection

pili = attachment/DNA transfer

flagellum = movement

Explain the general differences between bacterial, archaean, eukaryotic cells

bacteria and archaea are prokaryotes with no nucleus or membrane-bound organelles

eukaryotes have a nucleus and membrane-bound organelles

Recognize the structure and function of each organelle or cellular structure of eukaryotic cells

nucleus = DNA

ribosomes = proteins

Endoplasmic reticulum (ER) = protein/lipid processing

golgi = modifies/packages (like amazon)

lysosomes = digestion

mitochondria = ATP

chloroplasts = photosynthesis

vacuoles = storage

Identify cellular structures unique to plant and animal cells

plants have: cell wall, chloroplasts, large central vacuole, plasmodesmata

animals have: centrosomes/centrioles and prominent lysosomes

Describe the structure and function of the cytoskeleton in cells

protein network that maintains cell shape, organizes organelles, transports materials, allows cell movement

Explain the roles of different cytoskeletal elements in cells

microfilaments = movement/shape

intermediate filaments = strength

microtubules = transport, cell division, cilia/flagella

Describe the origin of mitochondria and chloroplasts in cells.

endosymbiotic theory: evolved from bacteria engulfed by ancestral eukaryotic cells

evidence includes double membranes, circular DNA, bacterial-like ribosomes

Describe the fluid mosaic model of membrane structure.

the membrane is a fluid phospholipid bilayer with proteins, cholesterol, and carbohydrates that can move within it

Describe signal transduction.

a cell receives an external signal through a receptor and converts it into an internal cellular response

Describe and give examples of the 5 functions of membrane proteins

transport, enzymatic activity, signal transduction, cell recognition, and cell-cell joining

Explain the relationship between membrane structure and selective permeability.

the hydrophobic membrane interior allows small nonpolar molecules through but blocks most ions and polar molecules, transport proteins help specific substances cross

Predict the movement of water molecules in different diffusion and osmosis scenarios.

water moves from lower solute concentration to higher solute concentration

hypotonic > water enters; hypertonic > water leaves; isotonic > no net movement

Describe the roles proteins play in the movement of molecules across a membrane.

channel proteins create passageways, carrier proteins change shape to move specific molecules across the membrane

20. simple diffusion

small/nonpolar molecules move down their concentration gradient; no energy

20. facilitated diffusion

polar molecules/ions move down their gradient through membrane proteins; no energy

20. osmosis

water moves toward the higher solute concentration; no energy

20. active transport

molecules move against their gradient using transport proteins; requires energy, usually ATP

20. endocytosis

cell takes materials in using vesicles; requires energy

20. exocytosis

cell releases materials out using vesicles; requires energy

Apply concepts from this chapter to the example of diabetes mellitus.

diabetes causes abnormal blood glucose regulation; type 1 involves little/no insulin, type 2 involves reduced insulin responsiveness

Describe how insulin is released into the blood.

high blood glucose cause pancreatic cells to release insulin by exocytosis

Describe the function of the GLUT protein.

transport glucose into cells by facilitated diffusion

Describe how GLUT protein gets into the cell membrane.

insulin signaling causes GLUT4-containing vesicles to fuse with the plasma membrane, inserting GLUT4 into the membrane

Describe how insulin affects cells that take up glucose.

insulin binds its receptor > activates signaling > GLUT4 moves to the membrane > glucose enters the cell

Describe signal transduction.

a ligand binds a receptor and triggers an intracellular signaling pathway that produces a cellular response

Describe the different forms of energy.

kinetic = energy of motion

potential = stored energy

chemical = energy in bonds

thermal = energy from molecular motion

State the two laws of thermodynamics and describe how they apply to cells.

1st law: energy cannot be created or destroyed

2nd law: energy transfers increase total entropy

Discern which of two different systems has greater entropy.

entropy measures disorder/randomness, a more disordered system has greater entropy

Identify how the terms anabolic, catabolic, endergonic, and exergonic relate to metabolic reactions

anabolic = builds molecules

catabolic = breaks molecules down

endergonic = requires energy

exergonic = releases energy

Summarize the ATP cycle and the role of ATP in the cell.

ATP > ADP + Pi releases energy

ADP + Pi > ATP stores energy

ATP provides short-term energy for cellular work

Explain the purpose of metabolic pathways and how enzymes regulate them.

metabolic pathways are sequences of enzyme-controlled reactions, cells regulate them by controlling enzyme activity

Explain how enzymes affect energy of activation of a reaction.

enzymes lower activation energy allowing reactions to occur faster, they do not change the reaction’s equilibrium

Describe enzyme function.

enzymes are biological catalysts that bind specific substrates at an active site and speed up reactions without being consumed

Describe the effect of environmental conditions on enzyme function.

temperature and pH affect enzyme activity, extreme conditions can change enzyme shape and cause denaturation

Describe the function and importance of coenzymes and cofactors.

cofactors are nonprotein helpers, often inorganic ions

coenzymes are organic helpers, often derived from vitamins

Summarize the relationship between the metabolic reactions of photosynthesis and cellular respiration

photosynthesis stores energy in glucose, cellular respiration releases energy from glucose to make ATP, their overall equations are roughly opposite

Write the overall equation of cellular respiration.

C6 H12 O6 + 6O2 > 6CO2 + 6H20 + ATP + heat

Explain the role of electron carriers in cellular respiration.

NADH and FADH2 carry high-energy electrons to the electron transport chain, their electrons provide energy to create the H+ gradient used to make ATP

Summarize the phases of cellular respiration and indicate where each occurs in the cell.

glycolysis = cytosol

preparatory reaction = mitochondrial matrix

citric acid cycle = matrix

ETC/chemiosmosis = inner mitochondrial membrane

Distinguish between the aerobic and anaerobic phases of cellular respiration.

aerobic requires O2, anaerobic metabolism does not require O2 and uses fermentation to regenerate NAD+

Describe the location and inputs and outputs of glycolysis.

occurs in cytoplasm

input = glucose, 2 ATP NAD+

output = 2 pyruvate, 2 NADH, 2 net ATP

Explain the energy-investment phase and energy harvesting phases of glycolysis

energy investment uses 2 ATP, energy harvesting produces 4 ATP and 2 NADH, net gain = 2 ATP and 2 NADH

Explain how ATP can continue to be produced in the absence of oxygen.

fermentation regenerates NAD+ so glycolysis can continue producing ATP without oxygen

Describe the advantages and disadvantages of fermentation

advantage = allows ATP production without O2

disadvantage = only produces 2 ATP per glucose

Summarize the inputs and outputs of the preparatory reaction and the citric acid cycle

preparatory reaction = pyruvate > acetyl-CoA + CO2 + NADH

citric acid cycle produces CO2, NADH, FADH2, and ATP

Describe how the proton gradient is created across the mitochondrial cristae.

The electron transport chain uses energy from electrons to pump H+ from the matrix into the intermembrane space, creating an H+ gradient

Identify the electron donation and final acceptor molecules of the electron transport chain

NADH and FADH2 donate electrons, O2 is the final electron acceptor and forms H2O

Explain the relationship between ATP synthesis and chemiosmosis.

H+ flows through ATP synthase down its gradient, the released energy drives ADP + Pi > ATP

Compare and contrast autotrophs and heterotrophs.

autotrophs make organic molecules from inorganic sources, heterotrophs obtain organic molecules by consuming or absorbing them

Explain the role of photosynthesis for all organisms on earth.

photosynthesis converts light energy into chemical energy, produces organic molecules, and releases O2. it supports most food webs

Write the overall chemical equation for photosynthesis

6CO2 + 6H2O + light > C6 H12 O6 + 6O2

Describe photosynthesis in terms of two sets of reactions in the chloroplast.

light reactions occur in thylakoid membranes and produce ATP/NADPH, the calvin cycle occurs in the stroma and uses ATP/NADPH to fix CO2

Describe the structure of a chloroplast.

chloroplasts contain an outer/inner membrane, stroma, and thylakoids - stacks of thylakoids are called grana

Name the pigments required to absorb light energy for photosynthesis.

chlorophyll a, chlorophyll b, and carotenoids absorb light energy for photosynthesis

Describe the structure of the thylakoid and how this contributes to photosynthesis.

thylakoids contain photosystems, electron transport chain proteins, and ATP synthase - their membrane allows an H+ gradient to form for ATP production

Identify the electron donor and electron acceptors in the light reactions.

H2O is the original electron donor, NADP+ is the final electron acceptor and becomes NADPH

Describe why the H+, proton, gradient across the thylakoid membrane is referred to as a storage of energy.

the concentration and charge difference across the thylakoid membrane stores potential energy, H+ flow through ATP synthase converts it into ATP

Describe the three phases of the Calvin cycle.

1) carbon fixation: CO2 + RuBP > 6C

2) reduction: ATP/NADPH produce G3P > glucose

3) regeneration: ATP regenerates RuBP

Explain how the product of the Calvin cycle is used to form the other molecules found in plants

G3P is used to make carbohydrates such as glucose and can also provide carbon skeletons for lipids, amino acids, and other molecules

Compare the overall chemical equations for photosynthesis and cellular respiration

photosynthesis: CO2 + H2O + light > glucose +O2

respiration: glucose + O2 > CO2 + H2O + ATP

Describe the similarities and differences between cellular respiration and photosynthesis

both use electron transport chains, proton gradients, chemiosmosis, and ATP synthase - photosynthesis stores energy and uses CO2, respiration releases energy and uses O2

hypotonic

water enters cell, lower solute concentration

hypertonic

water leaves cell, higher solute concentration

aerobic respiration

O2 required

photosynthesis

stores energy

cellular respiration

releases energy

fermentation

regenerates NAD+ > glycolosis continues