POB Lab - Exam 2

compound light microscope

visible light passes through a specimen, glass lenses, and is projected into the viewer's eye

magnification up to 1000x

dissecting microscope

used to look outside of specimens

magnification up to 50x

scanning electron microscope

studies the detailed external architecture of cell surfaces

black and white imaging

transmission electron microscope

studies the detail of internal cell structure

cell theory

all organisms are composed of one or more cells

cells are the basic living unit of structure

all cells come from other pre-existing cells

animal cell

does not have a cell wall or chloroplast and a small vacuole

plant cell

contains a cell wall, chloroplast and large vacuole

cytoskeleton

a network of fibers which organize the structure and activities of a cell

actin filaments

form projections in intestinal cells

allow for formation of pseudopods

provide the movement for muscle contraction

intermediate filaments

support nuclear envelope

help form cell-to-cell junctions

strengthens human hair

microtubules

help maintain cell shape

interact with motor molecules kinesin and dynein to cause movements of organelles

form spindle apparatus during cell division

endosymbiotic theory

- similar in size to bacteria

- both have their own DNA

- both are nearly identical to some free-living prokaryotes

- both bounded by a double membrane

- both contain genetic material

- both have ribosomes and produce protein

- both divide by splitting

fluid mosaic model

all cells are surrounded by the plasma membrane

selectively permeable : only certain, small substances can cross

maintains homeostasis

• lipids can pass through

the membrane and its proteins can shift back and forth because it isn’t completely solid or liquid

primarily made of protein and phospholipids

cytoplasm is inside the cell : made of salts, waters, and dissolved organic molecules

diffusion

there must be a concentration difference for this to occur

movement of molecules from high concentration to low concentration

solute and solvent both move

no energy is required

osmosis

movement of water across a semipermeable membrane from low concentration to high

only solvent moves

energy is required

channel proteins

integral

allow a specific molecule to freely cross the membrane

aquaporins allow water to freely move

can be closed, but can open if something needs to pass through

carrier proteins

integral

change shape to move across membrane

bind to other molecules and helps move the substance across the membrane

transports sodium and potassium ions across the cell membrane

cell recognition proteins

integral

made of glycoproteins that set off immune response in invading cells

signals to the body that the cell isn't foreign and leads to rejection of the cell

carbohydrates are attached to it, allowing it to be recognized

receptor proteins

integral

different receptors have different shapes, so they have to bind to a specific molecule that matches its shape to change activity

signal from outside of the cell changes activity

enzymatic protein

integral

each substrate has to attach to a certain thing for the reaction to occur

binds to a specific molecule and catalyzes (speeds up) or causes a reaction to happen

integral vs peripheral proteins

integral - embedded in the cell membrane

peripheral - sticking out; doesn't go through the membrane

hypertonic solution

more water is leaving than entering the cell

• higher solute concentration

cells will shrivel if placed in this solution

loss of shape = loss of function

not ideal for plant or animal cell

hypotonic solution

more water is entering

cells will swell or burst

preferred solution for plant cells

isotonic solution

solute concentration outside of a cell= solute concentration inside a cell

water isn't lost or gained

water equally moves in and out

preferred solution for animal cells

facilitated diffusion

molecules follow the concentration gradient down

carrier protein is required

• represented by the glucose carrier that can transport hundreds of molecules a second

energy is not required

reversible

active transport

molecules or ions combine with carrier proteins (pumps)

molecules move against (up) the concentration gradient

requires carrier protein and energy

ex : sodium-potassium pump

exocytosis

form of osmosis

macromolecules are transported out of the cell

happens as a result of regulated pathways

endocytosis

form of osmosis

macromolecules are transported into the cell

endergonic

input of energy

exergonic

output of energy

law of thermodynamics

energy cannot be created or destroyed, but it can be changed from one form to another

change from one form to another results in loss of energy

metabolism

sum of all the chemical reactions that happen within a cell

catabolism

breakdown of molecules

anabolism

building molecules back together

entropy

relative measure of disorder

eventually leads to death

constant input of energy will keep death and energy at bay

can never be decreased, only increased

more energy = more organized

more put together = less stable; has more potential energy

ATP

adenosine triphosphate

made from an adenine base, ribose sugar, and three phosphate groups

glucose catabolism provides energy to build up ATP

energy bond is found in or between the phosphate groups

enzymes

protein catalysts : speeds up chemical reactions

participate, but not used up

increase the rate of a metabolic reaction

binds with a substrate to form a complex

catalyze only one specific type of reaction

active site : small part of the enzyme that complexes with the substrate

metabolic pathway

series of linked reactions

begins with specific reactant that act as a substrate for specific enzymes

reactants are the input

reactions are strictly controlled

product of one reaction can become the reactant for the next

factors that affect enzymatic speed

substrate concentration, temperature, pH, enzyme activation, enzyme inhibition, enzyme cofactors

enzyme activation

activated by the addition or removal of phosphate groups

- kinase : adds phosphate

- phosphatase : removes phosphate

activated by removing part of the protein or associating with another protein/cofactor

enzyme inhibition

when the substrate is unable to bind to the active site of an enzyme

- as the product is used, inhibition is reduced and more product can be produced

end product of an active pathway binds to a site other than the active site

- binding causes the active site to change shape

- substrate unable to bind to the enzyme; pathway shuts down

enzyme cofactors

inorganic ions or nonprotein organic molecules that are required at the active site in order to work properly

chloroplast - innermost to outer most

thylakoid space, thylakoid, stroma, inner membrane, outer membrane

aerobic reaction

requires oxygen

reactants : oxygen and glucose (substrate)

products : carbon dioxide and water

anaerobic reaction

does not require oxygen

Cellular Respiration

a metabolic pathway that breaks down glucose and produces ATP

aerobic reaction

Glucose (C6H1206) + Oxygen (O2) —> Carbon Dioxide (CO2) + Water (H2O) + ATP

associated with the mitochondria

NAD+ and FAD

coenzymes

high energy electron transporters

temporarily store energy during cellular respiration

carries two hydrogen atoms and two electrons

FAD donates electrons to the electron transport chain

glycolysis

first phase of cellular respiration

*enzymes breakdown glucose into two

- occurs in cytoplasm

- inputs : ATP, NAD+, glucose, and ADP

- outputs : pyruvate, ATP, and NADH + H+

- net gain : 2 ATP, 2 NADH

- NADH is released to be used later in the electron transport chain

preparatory reaction

second phase of cellular respiration

*pyruvate gets transported to the mitochondria

- pyruvate attaches to coenzyme A to become acetyl coenzyme A

- CO2 is produced

- hydrogen atoms and electrons are removed from pyruvate and picked up to form 2 NADH

- 2 ATP are produced

- reaction occurs twice per glucose

- NAD+ gains two high energy electrons

NAD+ roles

gain two electrons

acts as a coenzyme

necessary for glycolysis

citric acid cycle (krebs cycle)

third phase of cellular respiration

- occurs in the matrix of the mitochondria

- remaining carbon is oxidized (electrons are lost) and CO2 is released

- input : 2 acetyl groups, 6 NAD+, 2 FAD, 2 ADP + 2P

- output : CO2, NADH, ATP

- reaction occurs twice

- coenzyme A is recycled to the preparatory reaction

chemiosmosis

the process of ions diffusing across a selectively permeable membrane

- usually hydrogen ions

requires a membrane to separate two compartments of the cell to allow for gradient formation

electron transport chain

last phase of cellular respiration

- occurs is the cristae of the mitochondria

- input : 10 NAD+, 2 FAD, 32-34 ATP

- NADH and FADH2 from previous stages give up electrons

- energy is released and captured as the electrons move from a higher energy gradient to a lower energy gradient

- energy is accumulated to pump hydrogen ions across the membrane (chemiosmosis)

- as hydrogen ions pass through, energy is released and captured to form ATP from ADP

- oxygen is used as an electron acceptor (last acceptor) and combines with hydrogen to produce water

- high energy electrons enter the system and low-energy electrons leave the system

- 36-38 ATP are produced

- carries electrons from photosystem || to photosystem |

photosynthesis

*Carbon dioxide + water -> glucose(carbohydrate) + oxygen

- the oxygen given off comes from water

- solar energy is converted into chemical energy of carbohydrates

- CO2 gains hydrogen atoms and becomes a carbohydrate

where does photosynthesis happen?

in the green parts of plants; mainly leaves

- water is taken up by roots and transported to leaves by veins

- CO2 enters through the stomata (openings in leaves)

- oxygen moves out

- light energy is absorbed by chlorophyll

function of pigment complex

captures solar energy and uses the energy to energize electrons

function of reaction center

energy is used to energize electrons even more

function of electron acceptors

accepts electrons until they are ready to go down the electron transport chain

photosystem |

- pigment complex energizes electrons; electrons bounce off of each other until they attach to the reaction center

- the reaction center energizes electrons even more and passes them to electron acceptors

- electron acceptors accept the electrons until they are ready to go down the electron transport chain

photosystem ||

water is broken into hydrogen and oxygen molecules (hydrolysis) to replace energized electrons

-pigment complex energizes electrons; electrons bounce off of each other until they attach to the reaction center

- the reaction center energizes electrons even more and passes them to electron acceptors

- electron acceptors accept the electrons until they are ready to go down the electron transport chain

noncyclic electron pathway

- electrons pass down electron transport chain

• water is split and oxygen is released

- energy is released to pump hydrogen ions into thylakoid space forming a gradient

- flow of hydrogen ions through ATP synthase creates ATP

sodium potassium pump

- 3 sodium ions bind to the protein channel

• channel changes shape, driving the ions through

- 2 potassium ions bind to the protein channel

• channel reverts back to its original shape

• potassium ions are released out of the bottom of the cell

- sodium ions bind to the protein channel again, initiating another cycle

- moving against gradient - low to high

- if a cell lacks ATP, this process would cease to operate

Phagocytosis

large particle matter is transported into the cell

things like viruses or food

Pinocytosis

small substances like macromolecules are transported into the cell

Receptor Mediated Endocytosis

a type of pinocytosis that involves a pit coated with proteins and receptors

somatic cells

body cells

apoptosis

programmed cell death

lysosomes

garbage can of the cell

digests food particles, wastes, cell parts, and foreign invaders

Which cellular structure is responsible for packaging materials with the cell?

golgi apparatus

motor proteins

transport cells across filaments

drag insulin-containing vesicles to the cell membrane along microtubules

degradation

substrate is broken down into smaller products

synthesis

substrate is bound together to form a larger product

when do muscles undergo fermentation?

when no oxygen is available

What tissue is specialized for photosynthesis in leaves?

Mesophylls

Light Reaction

*occurs in the thylakoid membrane

*solar energy is transformed into chemical energy

Steps :

1. Photosystem 2

2. electron transport chain

3. photosystem 1

4. NADP+ reduces to NADPH

• hydrogen ions are lost and passed to the electron transport chain to go through chemiosmosis

ATP and NADPH are produced

light-dependent reaction

Calvin Cycle

*series of reactions that reduce carbon dioxide to produce the carbohydrate glyceraldehyde 3-phosphate

*takes place in the stroma

*dependent upon a supply of carbon dioxide, NADPH, and ATP

*light-independent

3 steps

1. Carbon Dioxide Fixation : CO2 is attached to RuBP and produces a 6-carbon molecule that splits into 2 3-carbon molecules

- oxygen can slow the reaction down by preventing the CO2 from attaching; occurs three times

2. Carbon Dioxide Reduction : CO2 becomes CH20

- energy and electrons needed for this are supplied by ATP and NADPH

3. Regeneration of RuBP : for every three turns of the cycle, 5 G3P molecules are used to re-form three molecules of RuBP (18 carbons)

- remaining G3P molecules are used to make glucose, fatty acids, or glycerol

*the cycle must run six times to produce one molecule of glucose*

what is RuBP

sugar with two phosphates

what happens when a phosphate is removed from G3P?

the molecules can add fructose to form sucrose, the molecule that plants use to transport carbohydrates throughout their system

G3P can be converted to make up what?

the backbone of all molecules necessary to life`

What colors are absorbed by chloroplast?

red and blue

what colors are reflected by chloroplast?

green and yellow

nucleus

contains the cell’s DNA and is the control center of the cell

found in eukaryotes

contains chromatin

has a double membrane

nuclear envelope

outer membrane of the nucleus

nucleoplasm

fluid inside of the nucleus

nucleolus

center of the nucleus

nuclear pores

allow things in and out of the nucleus

ribosomes

the site where amino acids are hooked together to make proteins

endoplasmic reticulum

makes lipids, breaks down drugs and other substances, packages up proteins for release from the cell

rough ER

has ribosomes

synthesizing and folding proteins

smooth ER

no ribosomes

synthesizing lipids

mitochondria

break down food molecules to make ATP

powerhouse of the cell

absorbs and converts oxygen while releasing CO2 and water

chloroplasts

make food using the energy of sunlight

golgi apparatus

processes and transports materials out of the cell

vacuole

stores water and other materials

vacuole vs. vesicle

they serve the same purpose

large central vacuole pertains to the plant cell

the vacuole is larger

cilia and flagella

hairlike projections that aid in movement

only in eukaryotes

cilia is much shorter and more numerous

why can flagellum bend

they are made of microtubules that can bend by sliding past one another under the influence of the motor protein dynein

proteins are processed and modified in the interior of

the rough endoplasmic reticulum