BIOLOGY UNIT 2 FRW

What is the reactant for photosynthesis?

carbon dioxide and water

What are the products of photosynthesis?

carbohydrate and oxygen

What are the reactants of cellular respiration?

glucose (C6H12O6) and oxygen

What are the products of cellular respiration?

carbon dioxide, water, and ATP

What organisms perform glycolysis?

nearly all living organisms, in the cytoplasm of both prokaryotic and eukaryotic cells

Why do all living organisms perform glycolysis?

doesn’t directly use oxygen (anaerobic), it starts by breaking down glucose and nearly all energy comes from glucose

How does cyanide affect cellular respiration?

it blocks complex IV of the ETC, so oxygen can’t take the electrons

How is energy released from ATP?

ATP has 3 negatively charged phosphates

Phosphates repel each other

Water breaks off the terminal phosphate

ATP: ADP + Pi

Energy is released

Pi attaches to another molecule: phosphorylation

Phosphorylation activates the molecule for cellular work

Define oxidized

an electron is removed from a compound, which lowers its potential energy

Define reduced

 an electron is added to a compound, which raises its potential energy

What is a redox reaction?

oxidation and reduction occur together, so the pair is called an oxidation-reduction reaction.

Why is the net and gross total of ATP different in cellular respiration?

Four ATP are made in total (gross), but two ATP are spent in the first half to prepare the six-carbon sugar for cleavage. That leaves a net gain of two ATP.

What is the purpose of oxidative phosphorylation?

The ETC uses electron energy to pump H+ across the membrane. H+ flows through ATP synthase, which makes ATP from ADP and Pi. Produces about 90% of ATP.

Give 3 reasons why the number of ATP produced is not exactly known.

number of hydrogen ions the ETC complexes pump varies between species, pathways are used for other reasons, electrons are moved across the mitochondrial membranes

What is the purpose of O2 in the ETC?

Oxygen is the final electron acceptor

What step of cellular respiration produces the most ATP?

Oxidative phosphorylation (chemiosmosis)

What occurs in Glycolysis?

(Cytoplasm) one glucose becomes two pyruvate.

Phase one spends 2 ATP to trap and modify the sugar and split it into two three-carbon molecules.

Phase two makes 4 ATP and 2 NADH, for a net of 2 ATP and 2 NADH.

What happens in the citric acid cycle?

(mitochondrial matrix) after pyruvate is converted to acetyl CoA. Acetyl CoA’s two-carbon group joins oxaloacetate to form citrate. Eight steps of redox, dehydration, hydration, and decarboxylation produce CO2, one ATP, NADH, and FADH2, and regenerate oxaloacetate.

What happens in Oxidative Phosphorylation?

NADH and FADH2 deliver electrons to the ETC (complexes I-IV) in the inner mitochondrial membrane. The complexes pump H+ to build a gradient, oxygen accepts the electrons to form water, and ATP synthase makes ATP.

What three types of work can ATP be used for in the cell?

mechanical, transport, chemical

Identify and explain key adaptations of plants.

chloroplasts, chlorophyll

Why do leaves change colors in the fall? Use chlorophyll in your explanation.

Chlorophyll breaks down in fall. This reveals the carotenoids that were there all along.

What’s the general structure of a chloroplast?

Disc-shaped, membrane-bound thylakoids hold the light-dependent reactions.

How do cellular respiration and photosynthesis depend on each other?

Photosynthesis takes in CO2 and water and releases oxygen and carbohydrate. Respiration breaks down glucose using oxygen and releases CO2 and water.

Where do light-dependent reactions take place?

thylakoid membranes

Where do light-independent reactions take place?

stroma

How do light dependent and light independent reactions rely on each other?

Light-dependent reactions make ATP and NADPH, which light-independent reactions need to build carbs from CO2

Why are plants able to grow in the dark?

Plants contain both chloroplasts and mitochondria, so they rely on both photosynthesis and respiration and can function in light and dark.

Explain photosystem II

antenna pigments absorb a photon, pass the energy to the reaction center, takes electrons from water and sends them to ETC, produces oxygen,

Explain photosystem I

absorbs second photon, uses energy to move electrons from plastocyanin to NADP+, reduces to NAPH

How do enzymes affect your phenotype?

A different gene means a different enzyme, which means a different trait.

Why are most mutations neutral?

The code is degenerate, so many codons give the same amino acid.

Describe initiation in transCRIPTION

RNA polymerase and associated factors bind the promoter. In prokaryotes the σ subunit assists with this, and in eukaryotes transcription factors bind.

Describe elongation in transCRIPTION

mRNA is synthesized 5' to 3'

Describe termination in transCRIPTION

mRNA is released through rho protein or hairpin formation in prokaryotes

Describe initiation in transLATION

 the small ribosomal subunit binds the mRNA and begins at the start codon AUG, which specifies methionine.

Describe elongation in transLATION

charged tRNAs enter the A site, and their amino acid bonds to the amino acid at the P site, ribosome moves along in three-nucleotide steps.

Describe termination in transLATION

nonsense codon is reached, and a release factor dissociates the components and frees the protein

Why would protein synthesis steps differ between eukaryotic and prokaryotic cells?

prokaryotes use one RNA polymerase (core enzyme plus σ). Eukaryotes use three (I, II, III), and RNA polymerase II makes the protein-coding mRNAs

What is an initiation complex?

small ribosomal subunit + mRNA + initiator tRNA at the start codon AUG, and then the large subunit joins.

Define triplet

three nucleotides read together, specify amino acids.

Define codon

three consecutive nucleotides in mRNA that specify an amino acid or the release of the polypeptide chain.

Define anticodon

a three-nucleotide sequence in a tRNA that corresponds to an mRNA codon

DNA

deoxyribose, double stranded, stores info

RNA

ribose, single stranded, carries and uses info

How does the rough ER fit into protein synthesis?

Ribosomes on the rough ER make proteins for secretion or membranes

What role do ribosomes play in protein synthesis?

Ribosomes read the mRNA template in three-nucleotide steps

What is the central dogma?

DNA, mRNA, protein

What is the role of respiration in a cell?

It breaks down glucose to make ATP

Where does glycolysis take place?

cytoplasm

What goes “in” for glycolysis?

glucose

What goes “out” for glycolysis?

2 pyruvate, net 2 ATP, 2 NADH

Where does the citric acid cycle take place?

mitochondrial matrix

What goes “in” for the citric acid cycle?

Acetyl CoA

What goes “out” for the citric acid cycle?

CO2, NADH, FADH2, 1 GTP/ATP

Where does oxidative phosphorylation take place?

inner mitochondrial membrane

What goes “in” for oxidative phosphorylation?

NADH, FADH2, O2

What goes “out” for oxidative phosphorylation?

ATP, H2O

Aerobic respiration

uses O2 as the final electron acceptor in the ETC

Anaerobic respiration

no O2