ch 8-11 professor study guide

Photosynthesis

process where plants convert light energy (from the sun) to chemical energy

-process produces glucose and oxygen

In photosynthesis what is oxidized and what is reduced (water)

Water is oxidized to form O2

In photosynthesis what is oxidized and what is reduced (CO2)

Co2 is reduced to form glucose

where does photosynthesis take place

takes place in the chloroplast

-light dependent reactions in thylakoid membrane and Calvin cycle in the stroma

where does O2 take place

comes from H2O split during light dependent reactions

2 pathways in photosynthesis

light dependent reactions

Calvin cycle

Light dependent reactions

produce ATP and NADPH

splits water and releases oxygen

functions of light dependent reactions

-absorb light using pigments such as chlorophyll

-excite electrons with light energy

-split water, releasing oxygen

-establish a proton gradient across the thylakoid membrane

-produce ATP and NADPH

ATP

supplies energy for the reactions in the Calvin cycle including regeneration of RuBP

-supplies energy

NADPH

supplies high energy electrons and reducing power needing to convert carbon containing molecules into G3P

-supplies reducing power

Calvin cycle

uses carbon dioxide, ATP, and NADPH to produce G3P, a three-carbon sugar that can be used to make carbohydrates

Stroma

where Calvin cycle occurs and carbohydrates are produced

Thylakoid membranes

contains chlorophyll, photosystems, and electron transport chain needed for the light-dependent reaction

-help establish a proton gradient that is used to produce ATP

Grana

stacks of thylakoids that provide an organized membrane structure for the light dependent reactions

Carboxylation (carbon fixation)

CO2 is attached to RuBP by the enzyme rubisco, forming (3-PGA)

Reduction

ATP and NADPH provides the energy and reducing power needed to convert 3-PGA into G3P

Regeneration

remaning G3P molecules use ATP to regenerate the starting molecule, RuBP so the cycle can continue

G3P

three-carbon sugar produced during the Calvin cycle

-used to make larger carbohydrates

What is light

form of electromagnetic radiation that travels in waves and packets on energy called photons

what molecules convert light into chemical energy

pigments, specifically chlorophyll

Chlorophyll

pigment that absorbs light energy during photosynthesis

Chlorophyll when absorbs light

chlorophyll gets excited when it absorbs a photon

-absorption spectrum: graph showing how much light energy absorbs at various wavelengths

-action spectrum: a graph showing the rate of photosynthesis driven by different wavelengths of light

main pigments of chlorophyll

chlorophyll alpha and chlorophyll beta

why do plants have accessory pigments

they provide photoprotection by absorbing and safely dissipating excess light energy that could otherwise damage the plant

what is an antenna system

a cluster of hundreds of pigment molecules embedded in the thylakoid membrane that harvests light energy and funnel it toward a central reaction center

how electrons are transferred through the antenna systems

one pigment absorbs a photon, passes to it’s neighbor until the energy reaches the center chlorophyll

noncyclic electron transport

electrons flow from photosystem 2, and photosystem 1 to reduce NADP+ into NADPH, producing ATP, NADPH, and oxygen as a byproduct

-2 photosystems involved

-NADPH and ATP are synthesized via photophosphorylation

cyclic photophosphorylation

excited electrons returned to the photosystem they came from. This pathway produces ATP but does not produce NADPH or release oxygen through water splitting

noncyclic photophosphorylation

electrons move through the photosynthesis electron transport system and ultimately help reduce NADP to NADPH. Water replaces the electrons lost from the photosystem, and oxygen is released. ATP is also produced

How is a plant in the dark affected by photosynthesis

light- dependent reactions cannot operate normally because they pigments cannot capture the light energy needed to excite electrons

Reception

signal (ligand) binds to a receptor which is activated

Transduction

Signal is transmitted to the interior of the cell by a signal transduction pathway

Response

cell responds, by activating an enzyme or turning on transcription of a gene

Termination

signal stopped so response does not continue unnecessarily

Paracrine signaling

targets another cell with molecules in between, close but not connected

-short distance

Synoptic signaling

neuron communicating with a target cell across a specialized junction known as a synapse

Endocrine signaling

long distance signaling where cell released hormones into fluid that travel to other cells away

-travels through blood cells typically

Autocrine signaling

cell secretes molecule that binds to own receptor and causes a response, stimulating itself

-same cell

Photosystem

group of pigments and proteins organized in the thylakoid membrane

accessory pigments

absorb light and transfer energy toward the reaction center

reaction center

contains a special chlorophyll pair that uses the transferred energy to excite elections

Growth factor

protein that stimulates local cells to grow, divide, mature

-typically involved in paracrine signaling

intracellular signaling

inside the cell

intercelular signaling

outside the cell

receptors

proteins where signal molecules can bind

-located on the plasma membrane

hydrophilic signaling molecules

cannot pass through the plasma membrane so they bind to the membrane receptors

-facilitated diffusion or active transport

hydrophobic signaling molecules

can pass through the lipid bilayer and bind to intracellular receptors

-simple diffusion

polar and non polar receptors

both receptors go through shape change upon bonding with the ligand

G protein coupled receptors

cell surface transmembrane receptor that works with the help of a G protein, which binds energy-rich GTP

When ligand bonds to intercellular side the GPCR changes shape and activates protein which detaches and binds to an enzyme to trigger the next step

Receptor Kinases

activate signaling pathways involving the addition of phosphate groups to proteins. they can regulate growth and cell division

Ion channel receptors

control the movement of ions across the membrane in response to a signal, changing the cells electrical or chemical conditions

Ligand-gated ion channels

membrane receptors containing a region that act as a gate when the receptor changes shape

second messenger

small non-protein, water-soluble molecule or ion that relays a signal to a cells interior in response to a signaling molecule bound by a signal receptor protein (the first messenger)

how small signaling molecules like adrenaline cause big responses

protein pathways involve a cascade of enzymes activation leading to the activation of molecules in the next step

single amplified in a GPCR signaling pathway

-can activate multiple G protein molecules

-can produce large second messenger molecules like cAMP

-each protein kinase an phosphorylate and activate multiple copies of the next protein kinase in a series

Signaling errors and cancer

mutations that modify proteins in cell signaling can lead to excessive cell growth, division, and survival even in the absence of growth factor which is a hallmark of cancer

Role of Ras in cancer

protein relays a signal from growth factor receptors to a protein kinase cascade. mutations that make Ras permanently active causes continuous unregulated cell division even when no growth factor is present, driving cancer development

cell signaling

process which cells send, receive, and respond to messages

ligand

signaling molecule that carries the message

responding cell

cell that receives the message and produces a response

contact dependent signaling

when cells communicate through direct physical contact

transmembrane proteins

extend through the cell membrane and can interact with molecules on neighboring cells. these interactions allow cells to recognize each other and exchange information

Gap junctions

allow small molecules and ions pass through them for communication

cell structure and cell function related

cells structure helps it do its job

cell

basic unit of life

tissue

group of similar cells working together to do a job

organ

contains different tissues working together to perform a function

epidermis

outer skin layer

dermis

supports epidermis underneath

keratinocytes

makes keratin for protection

melanocytes

make pigment

fibroblasts

produces collagen for strength

cytoskeleton

supports the cell and helps it maintain its shape

microtubules

transport materials

help maintain cell shape, transport materials inside cells, move chromosomes during cell division, and support cilia and flagella

microfilaments

help with movement

-made of actin. help cells move

intermediate filaments

provide strength and stability. help cells resist tearing easily

dynamic instability

when microtubules grow and shrink. allows cells to change shape, move, and prepare for cell division

kinesin and dynein

motor proteins that carry materials along microtubules in different directions

cilia

move materials across cell surfaces

flagella

helps cell move

Cell adhesion molecules (CAM’s)

help cells attach to other cells or the extracellular matrix. they keep cells connected and organized into tissues

Adherens junctions

connect neighboring cells and help maintain shape

desmosomes

hold cells together strongly

hemidesmosomes

anchor cells to the underlying layer

tight junctions

prevent substances from passing between cells

cadherins

connect cells to other cells

intergrins

connect cells to the extracellular matrix

cell division

process where one cell makes more cells

growth, cell replacement, healing, reproduction

reproductive signal

tells the cell when to divide

DNA replication

copies the genetic material

segregation

ensures each new cell gets a full DNA copy

cytoplasmic division

splits the cells contents into two

binary fission

simple type of cell division used by bacteria

binary fission (1)

DNA attaches to the inner cell membrane

binary fission (2)

DNA replication begins at the origin replication

binary fission (3)

The new DNA attaches to the membrane

binary fission (4)

cell elongates, separating the DNA copies

binary fission (5)

new cell walls and membranes form in the middle

binary fission (6)

cell splits into two identical cells

prokaryotic cell division

have circular DNA in the cytoplasm and divide through binary fission