Biology 1406 Lecture Exam 3

What is the purpose of photosynthesis

make sugar for cellular respiration

How does cellular respiration compare to photosynthesis?

Photosynthesis is the flip opposite of cellular respiration

Photoautotroph

self-feeding organism that uses light energy from the sun

some are prokaryotes

plants

some are protists

what do SOME protists and plant cells have when they are photoautotrophs?

Chloroplasts

what makes chloroplasts green?

chlorophyll

what is chlorophyll?

green pigment that captures light energy

What type of energy is light energy?

kinetic energy

what is light described and measured in?

wavelength

What is the main pigment for photosynthesis?

chlorophyll a

what are some "accessory" also present in many cells?

chlorophyll b

carotenoids

what are some functions of accessory pigments?

they absorb the same kinds of light as chlorophyll a to power photosynthesis

they are also a sunscreen to protect against damaging light.

What does light energy do to the pigment molecules?

IT EXCITES THEM!

what do excited electrons have more of when light energy excites them?

Chemical energy

so, excited electron =

POWER

6CO2 + 12H2O --> C6H12O6 + 6O2 + 6H20

change in G= 686 kilograms

PHOTOSYNTHESIS

highly endergonic

oxidation reduction reaction

Where does photosynthesis take place

Chloroplasts

light reaction part of photosynthesis

occurs in thylakoids

produces chemical energy from the to power the calvin cycle

has an electron carrier NADP+ which turns into NADPH when it has excited electrons

calvin cycle

occurs in stroma and is light dependent

produces sugar

powered by electrons and ATP from light reactions

what is the sugar that is produced by the clavin cycle

glyceraldehyde 3-phosphate

Light reactions

1.) Linear electron flow

2.) 1st ETC

3.) Chemiosmosis

4.) ATP synthase

what is converted in the light reactions

H20---> O2

kinetic energy to chemical energy

-electrons and ATP come from H2O

H2O GETS OXIDIZED

what captures the light in the thylakoid membrane and what for?

photosystems and to excite electrons.

What are the two complexes in a photosystem

light-harvesting complex

reaction center complex

what does a light-harvesting complex have

chlorophyll a and accessory pigments

what does the reaction center complex have

chlorophyll a and a primary electron acceptor

The light reactions

two photosystems:

-photosystem I

-photosystem II

and they have the exact same structure and do the same thing at the same time.

electrons move through photosystem through

linear electron flow

electrons flow from H2O--> O2

linear electron flow

one way path of electrons in both photosystems and ETCs

The first electron transport chain powers

ATP synthesis

The second electron transport chain

reduces NADP+

How light reactions work

light hits the light harvesting system and pigment gets excited and energy transfers to other pigments which eventually transfers energy to chlorophyll a in reaction center. electrons are released from the pair of cholorphyll a pigments when they are excited.

What is NOT made in the light reactions

SUGAR IS NOT MADE

Electron flow from electron transport chains pump out what and power what

pump out H+ ions from stroma into thylakoid space to create concentration gradient which powers ATP synthesis- which is chemiosmosis

how do some photoautotrophs make extra ATP

cyclic electron flow- diverting e- back to first ETC so the repeat it and make more ATP

point of calvin cycle

make sugar- glyceraldehyde 3-phosphate

Calvin cycle reactants and products

CO2----> Sugar

what is calvin cycle powered by

NADPH and ATP from light reactions

first phase of calvin cycle

carbon fixation phase- traps carbon dioxide molecules

carbon fixation phase

CO2 gets into cell through simple diffusion through stomata pores on leaves

most plants are

C3 plants

C3 plants

not succulents or grass

how many CO2 captured per calvin cycle

3

what is carbon fixation is catalyzed by

the rubisco enzym= Ribulose bisphosphate carboxylase/ oxygenase

phase 2 of calvin cycle

reduction phase- gaining of electrons

reduction phase

uses ATP and NADPH from the light reactions to power the phase

makes 6 glyceraldehydes 3-phosphate but only one of those leaves the cycle.

where can glyceraldehyde 3 phosphate be used

glycolysis phase of cellular respiration- in the energy payoff phase.

can also be used to build larger carbohydrates

-glucose--> cellulose, starch

-sucrose--> cellular respiration in other plants

phase three of the calvin cycle

regeneration phase- which uses the 5 other glyceraldehyde 3-phosphates

regeneration phase

uses ATP from the light reactions

makes 3 ribulose bisphosphate to restart calvin cycle.

all cells must be able to...

communicate

cell to cell communication

cell signaling

cell signaling helps bacteria form structures of biofilms

which helps bacteria survive

cell signaling help with apoptosis

programmed cell death

what helps with cell signaling

biomolecules on the surface of the cell

how does cell signaling occur

direct contact

without direct contact

direct contact

cell junctions

cell-cell recognition

without physical contact

paracrine signaling

synaptic signaling

Endocrine hormonal signaling

cell junctions or plasmodesmata

permanent tunnels that allow diffusion of molecules and communication

cell to cell recognition

temporary

-neutrophils

-macrophages

paracrine signaling

synaptic signaling

endocrine signaling

insulin acts as a hormone

what does a target do during cell signaling

1.) Reception

2.) Transduction

3.) Response

Reception

signaling molecule binds to the receptor at the active site

like a substrate fits into the active site of an enzyme

signaling molecule

ligand

what is a receptor

most of the time they are proteins

all receptors have a very specific shape at the ligand binding site

can be intracellular or cell surface transmembrane

examples of cell-surface transmembrane receptors

ion channel receptors

receptor tyrosine kinase

g-protein coupled receptors

ion channel receptors

critical for muscles and neurons

part receptor and part channel

receptor tyrosine kinase

part receptor and part enzyme

tells cell when to start and stop properly dividing

two bars are dimers and they need to work in pairs

powered by a phosphate group from ATP

Transfers phosphate group to other proteins until ready to divide

g protein-coupled receptor

helps with seeing, smelling, and tasting

transduction

mobile intracellular receptors do it all by themselves but cell-surface transmembrane receptors use relay molecules

example of intracellular receptor

steroid-hormone receptors

aldosterone-

the ligand aldosterone has to go through membrane through simple diffusion then bind to receptor and change shape. Then receptor produces the response

cell-surface transduction

most boring game of telephone

what can relay signals in signal transduction?

ions

proteins

organcic molecules other than proteins lie cyclic AMP

What usually happens to signal transduction proteins to pass on the signal?

they proteins are phophorylated

Response

can be just about anything that that target cell is supposed to do or not supposed to do.

where could response occur

nuclear DNA

OR any other part of the target cell

- and response controls various cell functions.

multiple cell signaling pathways and their responses

one response

two responses

two pathways lead to one response- cross-talk

different receptor leads to a different response

cell signaling in the end

not straightforward

all designed to trigger apoptosis

cell division

binary fission

mitosis

meiosis

why is cell division important?

unicellular organisms- reproduction

multicellular organisms- reproduction

-growth and development

-tissue renewal

BEFORE A CELL DIVIDES IT MUST DO WHAT?

REPLICATE ITS DNA

Prokaryotic cell division

binary fission

Eukaryotic cell division

mitosis

meiosis

Binary Fission

faster than Eukaryotes

Replication of DNA happens at the same time as the division

-the cell elongates and needs more cell wall

-cell's chromosomes are replicated as the cell elongates

Results- daughter cells that are identical to the parent cell

goal of binary fission

to make more of original cell

what prevents cell from elongating

penicillin

Eukaryotic cell division is

much more complicated- more complex and way more DNA

multiple chromosomes

organized as chromatin

chromatin

protein spools with DNA wrapped around them

centromere

sister chromatids

mitosis daughter cells

are identical to parent cells

from somatic cells

meiosis daughter cells

are different from the parent cells

from sex cells

cell division is part of a timed cell cycle

dividing eukaryotic cells follow a cell cycle

cell cycle

interphase: G1, S, G2

M phase- mitosis or meiosis

G-

gap--> preparation time

S-

synthesis- 10 to 12 hours

DNA Replication

takes longer than prokaryote

happens BEFORE cell division

Go

healthy non-dividing cells like muscle cells are in this phase

they are not getting ready to or actively dividing

what controls cell cycle

cyclins- proteins

with help from cyclin-dependent kinase

cyclins tell cells

when to move on

if not ready, it will not continue past cell cycle checkpoint

if process is messed up, cyclin tells cell when to do apoptosis

Mitosis

2 daughter cells are divided from identical parent cell

animal somatic cells have 2 sets of chromosomes--> are diploid--> 2n