Emily Parrish Bio Processes Test 3

"Photo" in Photsynthesis

Conversion of solar energy into chemical energy (ATP)

"Synthesis" Photosynthesis

using inorganic nutrients to build organic molecules

What is the formula for photosynthesis?

6CO2 + 6H2O + energy --> C6H12O6 + 6O2

What is the input of photosynthesis?
What is the output?

Input: energy from sun, carbon dioxide, and water
Output: Glucose and oxygen gas

Organisms that carry out photosynthesis:

green plants, protists (Euglena), Bacteria (cyanobacteria), algae, and diatoms

What can carry out photosynthesis?

- Photoautotrophs: make enrgy from light, carbon dioxide, and water ("Auto" means: use inorganic nutrients to build organic molecules)
- Producers: produce ATP & organic molecules
- Terrestrial: green plants
- Aquatic/Marine

Marine phytoplankton consist of?
What are they responsible for?

algae, diatoms, cyanobacteria, euglena
- responsible for oxygen rich atmosphere we know today and credited with producing the most O2 through photosynthesis

Photosynthesis takes place where in Eukaryotes?
Prokaryotes?

Eukaryotes: chloroplasts
Prokaryotes: extensive internal membrane

How many membrane does chloroplast have?
What does the inner membrane structure look like

3: outer, inner, and thylakoid membrane
Inner membrane structure is folded in on itself

Thylakoid membrane

-special inner membrane means "sac"
- ETC embedded here

Thylakoid vs Granum /"grana"

thylakoid: single "thin mint cookie"
grana: 1 stack of "thin mint cookies"

Thylakoid Space

space inside the thylakoid
- H+ gradient established here

Stroma

- space outside thylakoid membrane
- calvin cycle is here
- this where the "synthesis" part of photosynthesis takes place

Pigments

-absorb some wavelengths of light and reflect others
- appear the color they REFLECT

electromagnetic spectrum

the range of wavelengths or frequencies over which electromagnetic radiation extends.

visible light spectrum

- the portion of the electromagnetic spectrum that is visible to the human eye
- ranges from 380 nm to 750 nm
- pigments in chloroplasts will either absorb or relfect these wavelengths of light

White light

all wavelengths of visible light are reflected
- why most molecules appear white

Wavelength

distance between one crest on one wave to same crest on next wave

2 important pigments used in photosynthesis

chlorophyll alpha and chlorophyll beta

Chlorophyll alpha

- the key light-capturing pigment that participates directly in the light reactions
- reflects more of a yellow green

Chlorophyll beta

- An accessory photosynthetic pigment that transfers energy to chlorophyll alpha
- reflects more of blue green

Carotenoids

- class of pigments
- do not function in photosynthesis
- reflect red, yellow, or orange
- proposed that they reflect excess sunlight to prevent sun damage to plants

Relationship between chlorophyll and carotenoids during the season change

- when trees go dormant chlorophyll dies first
- carotenoids can then be seen
- but then carotenoids also die and leaves fall of the tree

Photosystem II

- special pair of chlorophyll alphas called P680
- P680 is the wavelength of light it most efficiently absorbs
-electrons go down ETC
- H+ ions shuttled into thylakoid space establishing H+ gradient
- ATP synthase allows H+ to diffuse down gradient back into stroma
- ATP is regenerated via photophosphorylation
- P680 has donated its electrons to PEA and is now missing electrons: so it replaces them by:
- stealing electrons from water

Primary responsibility of photosystem II

generate H+ gradient and ATP

What happens to the water molecule when P680 steals electrons from it to replace the ones it lost?

the water molecule splits
- the oxygens then recombine to form oxygen gas
- this is why oxygen is released as a by-product

Primary responsibility of photosystem I

donate electrons to Calvin Cycle

Photosystem I

- special pair of chlorophyll alphas is called P700
-P700 is the wavelength that is absorbed most efficiently
- p700 electron jumps to PEA and
- electrons go to electron carrier in the stroma and is picked up by NADP to form NADPH
- p700 replaces its electrons by stealing electrons from the ETC

Light harvesting complex

- serves as the "hot dog bun"
-both types of chlorophyll are found here

Reaction Center Complex

- serves as the "hot dog"
- PEA found here
- special pair of chlorophyll Alpha are bound together

primary electron acceptor

in chloroplasts, an acceptor of electrons lost from chlorophyll a; found in the thylakoid membrane

Photophosphorylation

similar to oxidative phosphorylation in which there is an ETC but light drives electron transport chain and sunlight is converted into chemical energy

Summary of photosynthesis

1) light comes in, captured by light harvesting complex
2) light is absorbed by chlorophylls in light harvesting complex (absorb red and blue most efficiently)
3) energy from light is passed laterally from one chlorophyll to the next eventually reaching the chlorophyll alphas in RCC
4) when special pair of alphas absorbs the energy, electron jumps and is picked up by PEA

How is the imbalance of ATP and NADH corrected in the chloroplasts during photosynthesis? In other words, what happens when there is too much NADPH and too little ATP?

Cyclic flow of electrons which occurs in the Calvin Cycle

What happens in Cyclic flow of electrons?

NADPH takes electrons back to ETC and releases them
- ETC continues to run and generate ATP
- this decreases the levels of NADPH and increases the levels of ATP
Summary: generates additional ATP

What does the "photo" part or "light reactions) of photosynthesis supply to Calvin Cycle?

ATP and electrons

What is known as the "synthesis" part of photosynthesis aka the dark reactions?

The Calvin Cycle

Steps of the Calvin Cycle

1) Carbon Fixation
2) Reduction
3) Release
4) Regeneration

ribulose bisphosphate (RuBP)

5 carbon sugar with phosphate on either end and interacts with carbon dioxide

Carbon fixation

- carbon dioxide is attached to RuBP by the enzyme Ribulose bisphosphate Carboxylase (Rubisco)
- carbon dioxide is converted from gas to solid in this process
- 3 CO2 are inputted
- 1 Carbon Dioxide molecule is attached to each RuBP
- resulting with 6: 3 carbon molecules with an attached phosphate because the unstable nature causes them to split
- end first step with total of 18 carbons) (6x3=18)

Rubisco

- most abundant enzyme on earth
- responsible for carbon fixation in Calvin Cycle

Reduction

- electrons are gained
- ATP is used to phosphorylate 3 carbon compound
- ATP swoops in and drops off a phosphate
- molecule is destabilized so it accpets eelctrons from NADPH which becomes NADP
- when electrons are accepted, extra phosphate is expelled
- ends with 3 carbon compound w/ phosphate known as G3P
- this happens 3 times so total of 6 G3P molecules are produced

Release

1 G3P molecule is released
- it can easily be turned into glucose
- left with 5 G3P molecules
the product that is actually released during calvin cycle is G3P not glucose

Regeneration

- 5 G3P are turned into 3 RuBP by using ATP
- ATP swoops in and drops off a phosphate and leaves as ADP
- 3 RuBP are regenerated
- total of 15 carbons (5x3=15)
- 3 carbon dioxides were brought in and 3 carbons were released with the G3P total

Photorespiration

Reaction in which rubisco fixes (attaches) oxygen gas to RuBP instead of carbon dioxide
- this is BAD
- it wastes ATP and destroys RuBP

Stomata/Stoma

- means "mouth" or "pore"
- sites of gas exchange (oxygen released and carbon dioxide enters)
- water vapor also leaves through stomata

What type of environments does photorespiration most likely to occur? Why?

-Hot/dry weather
- plants close stomata to prevent water loss
- also prevents gas exchange from occurring so oxygen cannot be released and CO2 cannot enter
- oxygen levels rise and CO2 levels fall in the leaf
- which can lead to photorespiration

What mechanism does C4 plants use to prevent photorespiration?

- use a different enzyme in carbon fixation called PEPco
- PEPco has no affinity for oxygen so it cannot bind oxygen and cannot make this mistake: it specifically binds Carbon dioxide only
EX: grasses
- important bc they are the base of our food market: wheat, barley, oats, & corn

What mechanism do CAM plants use to prevent photorespiration?

- stomata open only at night and are closed during the day
- gas exchange only occurs at night
- carbon dioxide is collected and stored as an organic acid at night
- carbon dioxide is then released to Calvin Cycle during the day
- EX: succulents, pineapples, aloe plant

What are the 2 types of reproduction?

Sexual and asexual

Asexual

- 1 parent
- offspring genetically identical to each other and parent
-energy not needed to be devoted to finding a mate (more energy=more offspring more often)
-favored in stable environmental conditions
- MITOSIS most commonly associated with asexual reproduction
-ex: amoeba, plants (plants can reproduce asexually or sexually depending on environmental conditions)

sexual reproduction

- 2 parents
- offspring are a combination of genes from two parents
- not genetically identical to each other or parents
- time/energy spent finding a mate (less energy= less offspring less often)
- favored in unstable environmental conditions (more advantages for offspring)
- MEIOSIS most commonly associated with sexual reproduction
- ex: paramecia, mammals

IN which type of organisms is reproduction more complex?
Reproduction can exist on both the _____________ level and ___________________ level?

-Multicellular
- organismal & tissue level

MITOSIS

- parent cell divides to form two daughter cells which are genetically identical to each other & parent
- seen as asexual reproduction in single celled organisms
- also takes place in human body: replacement of tissues in multicellular organisms (EX: skin, stomach lining, fingernails, hair)
- also seen in embryotic development: after fertilization; single celled embryo becomes billion celled embryo through mitosis

Stages of Mitosis?

Interphase and Mitotic Phase

Interphase (Mitosis):
what are the 3 distinct phases?
What happens in all of these phases?
What happens after interphase?

- G1, S, G2
- in each phase, cytoplasmic components begin duplicating themselves (EX: centrosome, mitochondria, chloroplasts)
- about 90% of mitosis occurs during this phase
- if cells meet all requirements and make it through both checkpoints; they can enter mitotic phase

G1 phase of interphase (G1 checkpoint)

-G1 checkpoint is at the end of G1 phase
- checks genomic DNA for errors and fixes the errors in the genomic DNA before it is copied
- then sent to S phase for copying

S phase of interphase (synthesis)

DNA duplication occurs in this phase after G1 checkpoint fixes errors

G2 phase of interphase (G2 checkpoint)

- checks the new DNA COPIES for errors adn fixes any errors
- If DNA damage cannot be corrected at either checkpoint it enters a state known as G0

G0 phase

- nondividing state
- cell can live in this state but cannot divide
- Ex: muscle tissues live in this state- when muscle is damaged, must wait for cell to fix itself because new cells cannot be made
- EX: nervous cells do not make new cells, so nerve damage is permanent damage and these cells are limited in their ability to repair themselves

Mitotic phase?
What are the phases of it?

stage of the cell cycle when a cell is actively dividing and the DNA of cell's nucleus splits into two equal sets of chromosomes
- about 10% of cell division occurs during this phase
Steps: Prophase, prometaphase, metaphase, anaphase, telophase, & cytokinesis (overlaps with telophase)

Chromatin

active uncoiled state of DNA
- DNA appears this way during interphase

Super coiled DNA

the DNA is easily identifiable and appears as the general "X" shape we refer to when talking bout chromosomes

Chromatids?

in prophase there are 2 sister chromatids that are attached
- an original chromosome and its copy

The centromere is a region in which

chromatids are attached to one another
- also where the microtubules of spindle attach to chromosome

Prophase

- chromosomes start to supercoil ( become visible) (but they are still indistinct)
- original chromosome and its copy are attached at centromere and considered 1 chromosome
- centrosomes begin to form mitotic spindles
- centrosomes start to migrate to opposite ends of cell

Prometaphase (Mitosis)

- chromosomes are more distinct
- spindle microtubules have formed (kinetochore and non-kinetochore)
- nuclear envelop fragments/breaks open
- chromosomes spilled into the cytoplasm to interact with spindles
- kinetochore microtubules will attach to chromosomes

kinetochore microtubules (KMT)

microtubules of the mitotic spindle that attach to condensed chromosomes at their centromeres

non-kinetochore microtubules (NKMT)

- do not attach to chromosomes
- instead, they attach to each other (1 from each end of spindle)

Metaphase

- centrosomes are at either end of poles & opposite from each other
- spindles finish binding & asters anchor at the plasma membrane
- KMT push and pull chromosomes until they are lined up on an invisible plane in middle of the cell called metaphase plate
- there is a mitotic checkpoint here
- everything else waits until chromosomes are lined up

Asters

spindle microtubules that anchor to the plasma membrane

Anaphase

- sister chromatids separate from each other
- each sister chromatid is its own molecule and called a chromosome
- the cell now has twice the amount of DNA
- KMT get shorter to separate the two sets of DNA
- NKMT get longer to elongate the cell and further separate the two sets of DNA

Telophase

- nuclei reform
- spindle breakdown
- chromosomes unwind and become indistinct
- cell becomes a peanut shape because of cytokinesis

Cytokinesis

-division of cytoplasm
- overlaps telophase
- 2 types depending on whether or not the organism has a cell wall

Cytokinesis in organism without cell wall, that is animal cell/animal like cell?

-ring of microfilaments form around the middle of the cell called cleavage furrow
- microfilaments are contractile so the ring contracts and pinches the cell in two
- gives the cell the peanut shape
- identifying characteristic is the cleavage furrow

Cytokinesis in organism with a cell wall (plants, fungi, etc.)

- cell wall cannot be pinched
- the nuclei become active and their first task is to build a new cell wall and new plasma membrane to divide the cytoplasm in two
- identifying characteristic is called the cell plate
- cell plate= half completed cell wall

What is cancer regarding cells?
What happens when they form?

-error of cell division
- they form when the cells no longer recognize the signals to stop dividing
- the tissues in our body have multiple signals that tell cells to stop dividing and cancerous cells do not recognize any of them

when cancer cells form:
- it constantly divides and produces others cells that do not stop dividing eventually forming a mass of cells

What is a tumor and what are the two types?

tumor: mass of cells that do not know they are supposed to stop dividing
two types: benign and malignant

benign tumor

- growth is restricted to a basement membrane but they can still get big because the basement membrane can grow as well
- like a sac and needs to be removed
- easy to surgically remove
- membrane of tumor is attached to organs in our body

Malignant tumor

- this is what the word "cancer" most often refers to
- growth is NOT restricted to basement membrane
- cancerous cells grow all over the organ it is attached to
- not easy to treat surgically
- may metastasize
- treatment: chemotherapy

What does it mean when a cancerous cell metastasizes?

- one cell or a couple of cells will break off the main tumor and be carried away to remote locations in the body
- the main tumor prevents the growth of the metastasized cells as long as the main tumor is still present in the body
- once the main tumor is removed, the metastasized cells start dividing

Chemotherapy treatment characteristics:

- targets rapidly dividing cells
- drug is attached to glucose molecule and when the cells use the glucose the drug can kill the cancer cells
- the metastasized cells will begin to grow as the main tumor begins to die: this allows the drug to target the metastasized cells as well

What is the most effective way to kill cancerous cells today?

- immune system is most effective at killing cancer cells
- white blood cells are forced to recognize cancer cell and fight it

Meiosis

- parent cell undergoes 2 rounds of cell division to produce a total of 4 daughter cells
- each daughter cell has half the genetic content of the parent
- form of sexual reproduction that produces the gametes such as sperm and egg

Genome

complement of DNA required for a species to survive

diploid cell

two complete sets of DNA in genome (Ex: humans)

Haploid

1 set of DNA in genome (bacteria, fungi)

Alleles

- different versions of same gene
- 2 copies of each gene (1 from mom & 1 from dad)
- EX: eye color, hair color, etc.

homologues (homologous chromosomes)

-the same chromosome but inherited from different parents (1 from each)
- look the same and carry the same genes
- not genetically identical because they have different alleles
EX: Chromosome 1 from mom, chromosome 1 from dad= complete pair of chromosomes

What does Meiosis form? Why is this important?

- forms haploid gametes from diploid germ cells
- formation of gametes is critical to diversity and variation

Steps of Meiosis (Meiosis 1 and Meiosis 2)

Interphase
Meiosis I: Prophase I, Metaphase I, Anaphase, Telophase I/Cytokinesis
Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II/Cytokinesis

Prophase I

-association of homologues: homologues bind together
- 4 sister chromatids bound together so crossing over occurs

Crossing over occurs in Prophase I of Meiosis. What is this and why is it important?

- segments of DNA is swapped between the homologues
- important because it increases genetic variation by creating new combinations of alleles

Metaphase I (Meiosis)

- homologues arranged on metaphase plate
- independent assortment: creating new combinations of chromosomes

Anaphase I (Meiosis)

- separation of homologues
- sister chromatids are still attached

Telophase I/Cytokinesis (Meiosis)

- cytokinesis may or may not occur
- produce two daughter cells
- daughter cells considered haploid

Prophase II

same as prophase I

Metaphase II

same as metaphase I

Anaphase II

- basically the same as anaphase I except
- in anaphase II: the sister chromatids separate

Telophase II/Cytokinesis

4 haploid daughter cells are produced