Photosynthesis #6: BIO 1A (editing)

what cellular activities require energy?

• metabolizing (‘breaking down’ molecules)

• synthesizing (‘buildin’) molecules

• fighting pathogens

• exporting wastes

• cell division & growth

• reproduction

Process of breaking down carbon based food

animals: digest food first

plants: create food in simple form (glucose) - no need for digestion

energy extracted form food molecules through cellular respiration (occurs in mitochondria)

Energy transformation

plants transform solar energy into chemical energy stored within organic molecules (photosynthate)

sunlight (solar energy): 6CO2 (carbon dioxide) + 6HH2O (water) → C6H12O6 (glucose) + O2 (oxygen)

chemical energy (atp)

energy available in molecules that is released in a chemical reaction

• chemical energy (potential energy) in amylose (polysaccharide in starch) due to structure of amylose molecules

ATP (adenosine triphosphate)

immediate energy source that fuels all activities of all organisms

• potential chemical energy isstored in chemical bonds in ATP

• - fuels all cell activities

Where are ATP molecules stored?

In phosphate bonds

• adding phosphate group to ATP required alrge amount of energy, created high-energy chemical bonds

• breaks high-energy phosphate bond, releases energy

• ATP is a fragile molecule

What is ATP ‘used” to break?

used by breaking a high-energy bond to release energy

• breaking phosphate bond changes ADP to ATP

• Energy released is used by cell to do ‘work’

What energy is used to recharge ADP to ATP?

• ADP ‘recharged’ to ATP by adding a phosphate group to ADP

• recharged from diphosphate to triphosphate

• ADP → ATP comes from breakdown of glucose in cellular respiration

What is ATP? Where is ATP? Where does it come from?

• a type of molecule that functions as the cell’s ‘rechargeable battery’

• ATP is in every cell

• ATP is recharged from ADP through cellular respiration

What does ATP do? How does it work? How is it recharged?

• ATP molecules provides the energy necessary for everything cells do

• ATP is used by breaking a high-energy bond to released energy, changing ATP to ADP

• energy from breaking glucose down is used to recharge ADP to ATP; 3rd phosphate group added to ADP

How many molecules are produced from 1 glucose molecule through cellular respiration?

38 ATP molecules

Where does glucose come from?

Through the process of photosynthesis where plants transform the energy of sunlight into chemical energy stored within organic molecules → glucose+oxygen byproduct

What organisms performs photosynthesis?

performed by plants, algae, and cyanobacteria

• all photosynthetic organisms have chlorophyll pigments that capture light energy form the sun, also possess other pigments to capture solar energy

How do eukaryotic and prokaryotic organisms perform photosynthesis differently?

Eukaryote organisms have chloroplasts while prokaryotes have no chloroplasts

Photosynthesis and cellular respiration reactions

Photosynthesis (builds glucose → anabolic) : CO2 + H20 + energy from sunlight to produce glucose + O2

• CO2 + H2O = C6H12O6 (glucose) + O2

Cellular respiration (breaks down glucose → catabolic) : uses glucose + O2 To produce ATP + heat + H2O + CO2

• C6H12O6 (glucose) + O2 = ATP + heat + H2O + CO2

How is glucose broken down?

glucose is broken down through cellular respiration to fuel plant growth and activities

• excess glucose stared as starch

Where does most photosynthesis take place?

Most photosynthesis takes places inleaves

• Chlorophyll - important light-absorbing pigment located within chloroplasts

• chloroplasts concentrated in upper surfaces of leaves in most plants

What does the stomata do?

Gas exchange is regulated through stomata— small openings on the bottom of surface of leaves

• CO2 gas is absorbed through stomata

• O2 gas and water vapor released through stomata

Chlorophyll location

in thylakoid membrane within chloroplasts within mesophyll cells within leaf and other green parts of plant

Solar energy wavelengths

solar energy measures as waves

• shorter wavelengths (violet-blue) have higher energy

• longer wavelengths (red) have lower energy

Why are plants green?

chlorophyll pigments absorb violet-blue and red light, therefore reflect green light

What are the two stages of photosynthesis in the chloroplasts?

• Stage 1. Light dependent readtions (LDR): provides energy for calvin cycle

  • convert light energy into chemical energy (ATP & NADPH)

• Stage 2. Calvin cycle: energy from LDR used to synthesize glucose

  • uses chemcial energy from LDR to power the synthesis of glucose molecules

Stage 1: Light dependent reactions (LDR) - water required :p

• LDR converts light energy into chemical energy

• occurs within photosystem - group of pigment molecules and proteins (in thylakoid membrane) - like a light gathering antenna

• photon (unit of light) absorbed by 1st chlorophyll molecules in photosystem → electron excited & break free; H2O = O2 + 2H

• O2 waste product released through sotmata

• electron (transport of H+ ions) now passed down series of proteins (stroma into thylakoid) that makes up an electron transport chain creating (portential) energy

Stage 1: Light dependent reactions (LDR)  Steps

1. light energy absorbed

2. water molecules split
   electron donated by 1st chlorophyll replaces by splitting H2) molecules into O2 + 2H

3. O2 released as waste product

4. energy-carrying molecules ATP & NADPH produced
   electron transport chain of H+ ions from stroma to thylakoid of higher ion concentration to low ion concentration → creates potential energy

Produces: ATP (energy carrier), NADPH (energy carrier), O2 (waste product)

Stage 2 Photosynthesis Calvin Cycle

• calvin cycles uses chemical energy generated by LDR to produce glucose

• energy needed to synthesize glucose comes from LDR (ATP & NADPH)

• energy from ATP & NADPH is used to fix carbon and convert it into glucose

• 6 molecules of CO2 fixed to create 6-carbon glucose molecules

• ADP & NADP+ are then returned to LDR and are recharged

Carbon fixation: carbon is ‘fixed’ from it's inorganic form (gas) into organic molecules (glucose)

Carbon cycle

plants are net producers of atmospheric O2 and net consumers of CO2

• photosynthesis consumes CO2 and releases O2

• cellular respiration consumes O2 and releases CO2 as a byproduct

Cycle of carbon dioxide production and consumptions in plants

organisms produce CO2 as a byproduct of cellular respiration

• plants release some of CO2 into atmosphere

• platns consume some of the CO2 (produced by their own cellular respiration) in photosynthesis

• plants take in additional atmosphere CO2 through stomata (consumed in photosynthesis)

Cycle of oxygen production and consumption in plants

net producer of O2

• plants release O2 through stomata, byproduct of photosynthesis 

• some of the O2 from photosynthesis used for cellular respiration

• plants also take in atmospheric O2 to perform cellular respiration

Light compensation point

level of light intensity at which rate of photosynthesis = rate of respiration

Asexual reproduction

• reproduction involving only one parent

• offspring genetically identical to parent (clones)

• rapid & effective, no need to find mate

• produces more offspring than sexual reproduction

Sexual reproduction

• combines genes from two different individuals to form new indv.

• haploid gametes fuse in fertilization

• gametes produced through meiosis

• offspring not identical copies of parents

Ploidy

number of complete sets of chromosomes in nucleus of each cell

n = number of chromosomes in one complete set

• organisms vary in chromosomes number

Haploid (n) cells

1 set of chromosomes in nucleus

Diploid (2n) cells

2 sets of chromosomes in nucleus

Meiosis “overview”

Diploid parents cell undergoes 2 rounds of cell division: Meiosis I & Meiosis II

• Reduction division: Meiosis produces 4 haploid cells from the original diploid parent cell

• produces genetic diversity - haploid daughter cells are genetically distinct from original parent cell and from each other

How do prokaryotes produce?

reproduce asexually through binary fission (form of cell division)

Cyanobacteria

• prokaryotic organisms common in aquatic and terrestrial ecosystems

• named for the blueish pigment phycocyanin, use to capture light energy in photosynthesis pigments (not all are blue & pigments not contained within organelles)

• abundant components of marine and freshwater plankton

• ecologically essential, accounting for much of primary production occurring on earth

• photoautotrophs, use carbon dioxide and solar energy to produce their own carbon-based food (glucose)

• only photosynthetic prokaryotes

Autotrophs

organisms that produce their own carbon-based good

Heterotrophs

organisms that acquire their carbon-based food by consuming other organisms or substances produced by other organisms

Endosymbiosis

process where chloroplasts originating as symbiotic cyanobacteria were incorporated by ancient unicellular eukaryotes as organelles sin

• symbiosis in which one of the symbiotic organisms lives inside the other, leads to mutually beneficial relationship

cellular organization for cyanobacteria

• some exist in purely unicellular while others aggregate into colonies

• colonies taking form of filaments, sheets, or hollow spheres

• allow some differentiation of function among individual cells that make up colony

• don’t represent multicellularity

Dietary use of cyanobacteria

• Spirulina is a type of cyanobacterium

• high in protein

• imoprtant food source

Volvox

• colonial freshwater green algae in group chlorophyta

• photosyntheic eukaryotes, belong to larger group archaeplastida

• serve as importat food source for aquatic microorganisms

cellular organization volvox

idgaf !!

Haplontic life cycle

• only multicellular stage is the haploid gametophyte

• diploid phase, zygote → not multicellular (not referred to as ‘generation’ which would imply it’s multicellular

• zygote: doesn’t grow via mitosis to become multicellular sporophyte → undergoes meiosis to produce haploid spores

Haplodiplontic life ccle

All land plants have a haplodiplontic life cycle

• characterized by alternation of two different multicellular generations: diploid sporophyte gen and haploid gametophyte gen

• generation refers to multicellular plant

• sporophytes are multicellular diploid plants

• gametophytes are multicellular haploid plants

variation in haplodiplontic life cycle

dominance - live longer, generate offspring over mult. seasons, dom. gen.

nutritional dependence - gen. produces its own carbon- based food through photosynthesis (gen is ind.) if acquires much or all of its carbon based food from other gen (dependent)