BIO EXAM #3

Converts solar energy into chemical energy

Goal of photosynthesis

Plants, algae, and some protists

In what organisms does photosynthesis happen?

Autotrophs

“Self-feeders” that sustain themselves w/o eating anything from other organisms

Heterotrophs

Obtain organic material from other organisms

Chloroplasts

Where does photosynthesis occur?

Cells of mesophyll (interior tissue of leaf)

Where in plants are chloroplasts found?

Stroma

What are chloroplasts surrounded by?

Thylakoids

Connected sacs in chloroplasts

Grana

Stacks of thylakoids in columns

Chlorophyll

Pigment that gives leaves their green color resides in thylakoid membranes that absorbs light

Endergonic

What type of reaction is photosynthesis?

Oxidized

What happens to H2O in photosynthesis?

Reduced

What happens to CO2 in photosynthesis?

Reduced to NADPH

What happens to NADP+ in the light reactions?

Light reactions and Calvin cycle

Two parts of photosynthesis?

Wavelength

Distance between crests of electromagnetic waves

380 nm to 740 nm

Nm for visible light?

Photons

Particles that are in light?

True

T/F: Shorter wavelengths = more energy

Violet-blue and red light

What light does chlorophyll absorb?

Chlorophyll a, chlorophyll b, carotenoids

3 types of pigments in chloroplasts

Chlorophyll a

Main-light capturing pigment

Chlorophyll b

Accesory pigments

Carotenoids

Group of accessory pigments that reflect yellow and orange becaus they absorb violet and blue-green light

Excited state

When pigment absorbs light, electron goes from ground sate to what? (unstable)

Fluorescence

After electron falls back down to ground state, what is released?

Photosystem

Consists of reaction-center complex surrounded by light harvesting complexes

Reaction-center complex

Association of proteins holding special pair of chlorophyll a molecules and a primary electron acceptor

Light-harvesting complex

Various pigment molecules bound to proteins (transfer energy of photons to the chlorophyll a molecules in the reaction center)

Primary-electron acceptor

What in the reaction center accepts excited electrons?

Photosystem II and Photosystem I

Two types of photosystems in thylakoid membrane?

P680

Other name for photosystem II

P670

Other name for photosystem I

Linear electron flow and cyclic electron flow

Two possible routes for electron flow

Linear Electron FLow

Primary pathway for electron flow, involves both photoystems and produces ATP and NADPH using light energy

Cyclic Electron Flow

Only uses PSI, only produces ATP, photoexcited electrons cycle back from Fd to cytochrome comple instead of being transferred to NADP+

Carbon Fixation, Reduction, Regeneration

Three phases of Calvin Cycle

3 times

How many times does calvin cycle have to take place for one G3P?

RuBP (5-carbon ribulose biphosphate)

CO2 is added to what in the Calvin Cycle?

Rubisco (RUBP carboxylase-oxygenase)

What helps add Co2 to RuBP?

3-phosphoglycerate

What is 6 carbon split into? (3 carbon)

G3P sugar

What does 3-phosphoglycerate turn into with help of ATP and NADH?

6 molecules of G3P

How many molecules of G3P are produced?

5

How many molecules of G3P go back into RuBP?

Photorespiration

Process where rubisco binds O2 to RuBP instead of Co2

C3 plants

What type of plants does photorespiraton usually happen? (hot, dry plants as plants close stomata)

C4 plants

On hot days, what type of plants PARTIALLY close stomata, conserve H2O and reduce CO2?

Bundle-sheath cells

Where does photosynthesis happen in C4 plants?

CAM plants

What kind of plants open stomata at night and close during the day? (take in CO2 into vacuoles) (crassulacean acid metabolism)

Where do the light reactions occur?

Thylakoid membranes

Where does the calvin cycle occur?

Stroma

Signal reception, signal transduction, cellula response

Three steps of cell communication

Ligand

Signaling molecule

Receptor protein

Molecule to which receptor binds to

Ligand and receptor protein

Communication requires:

Signal transduction

Interaction between ligand and receptor protein initiates?

Intracellular and Plasma Membrane

Two locations of signal receptors

Hydrophobic

What type of ligands can cross the membrane?

Direct contact, paracrite signaling, synaptic signaling

Types of local signaling

Endocrine signaling

Type of long distance signaling

Signal reception

Target cell detects a signaling molecule that binds to receptor protein

Signal transduction

Binding of signaling molecule alters receptor and intiates signal transduction pathway

Cellular response

Transduced signal triggers specific response in cell

True

T/F: Most signal receptors are plasma membrane proteins

G-protein-coupled receptor, Receptor tyrosine kinases, Ion Channel Receptors

3 Main Types of Membrane Receptors

G-protein coupled receptor

Transmembrane receptor that works with the help of G protein, G-protein binds energy-rich GPT (GDP bound=inactive)

Receptor tyrosine kinase

When ligand connects ,they dimerzie, phosphorylation happens

Ion Channel Receptors

Ligand-gated ion channel receptor acts as gate that opens and closes when receptor changes shape

Intracellular receptors

Receptors found in cytoplasm or nucleus of target cells, complex can act as a trasncription factor, turning genes on and off

Signal transduction pathway

Activated receptor activates another protein, which activates aother, and so on, until protein produces response activated

Protein phosphorylation

Protein kinases transfer phospahtes from ATP to protein

Phosphorylation cascade

Many relay molecules in protein phosphorylation

Dephosphorylation

Protein phosphatases rapidly remove phosphates from proteins

Second messengers

Small, non-protein, water-solube molecules or ions that spread by diffusion

cAMP, adenylyl cyclase, calcium ion

Types of second messenger

cAMP (cyclic AMP)

Second messenger that is produced from ATP

Adenylyl cyclase

Enzyme in plasma membrane, converts ATP to cAMP

Calcium ion

Widely used second messenger

Transcription factor

Final activated molecule in signaling pathway

Apoptosis

“Programmed” cell death (terminates cell signal)

Reproduction, Growth, Wound Healing, Cell replacement

What is cell division necessary for?

Sister chromatids

Two identical, attached copies of a single replicated chromosome formed during the S phase of the cell cycle

Genome

All DNA in cell constitutes the cells’s?

Chromosomes

DNA molecules in cell are packaged into?

Karyotype

Array of chromosomes of an individual

Diploid

Cell that has two sets of chromosomes (2n=46) (somatic cells)

Haploid

Cell has one set of chromosomes (n=23)

Homologous chromsomse

Pairs of chromosomes in a diploid cell, carries the same genes but may have different alleles

Chromatin

Complex of DNA and protein that condenecses during cell division, eukaryotic chomrosomes consist of this

Cohesins

Sister chromatids are attached along the lengths by this

Centromere

Narrow waist of chromosome

Binary fission

Type of cell division used by prokaryotes, plasma membrane pinches inward, dividing cells into two

Interphase and M-phase

2 Main Parts of Cell Cycle

G1, S, G3

Three stages of Interphase

G1

Primary growth phase, LONGEST stage in Interphase

S

Stage were DNA gets replicated

G2

Stage where cell further grows, microtubles become organized

Hour

How long does the M phase typically take?

G0

Resting phase, where cells exit the cycle and stop dividing

Prophase, Prometaphase, Metaphase, Anaphase, Telphase

5 Phases of Mitosis