Photosynthesis, Cell Structures, and Genetic Code: Key Concepts for Biology

What is the entire range of wavelengths of electromagnetic radiation called

Electromagnetic spectrum

The light reactions occur where in the chloroplast?

Thylakoid membranes

Outputs of Calvin Cycle

Sugar (G3P), ADP, NADP+.

How do the light reactions get electrons?

Water (H₂O is split)

What colors of light does chlorophyll absorb best?

blue and red light.

What colors are LEAST absorbed by chlorophyll?

Green and yellow (reflected).

Adapted for hot, dry environments (they open stomata at night).

CAM plants

What is the role of NADPH in photosynthesis?

Carries high-energy electrons to the Calvin cycle.

What happens in Photosystem I (PSI)?

Electrons are re-excited & transferred to NADP+ → NADPH

Which kingdom does NOT have cell walls?

Animalia

Why do some cells have more mitochondria than others?

They need more energy (ATP)

Similarity of chloroplasts and mitochondria

Both have circular DNA, double membranes, and make ATP

What is the fluid mosaic model of the cell membrane?

A dynamic phospholipid bilayer with proteins, carbs, cholesterol

What is a frameshift mutation and what does it cause?

Insertion/deletion of nucleotides; nonfunctional protein

What two things does tRNA do?

Carries amino acid, Matches anticodon to codon

What happens at the A, P, and E sites of ribosomes?

A = tRNA enters, P = peptide bond forms, E = exit. First tRNA enters P site.

Difference between polypeptide and protein

chain of amino acids; folded (3D) structure

Difference between translation & transcription

Translation = RNA → protein, Transcription = DNA → RNA.

Why do all organisms make proteins the same way?

It shows universality of genetic code → common ancestry

Why is photosynthesis important for life on Earth?

Produces oxygen and food (sugar)

Responsible for absorbing wavelengths of light (chlorophyll and carotenoids).

Pigments

Product made by the Calvin cycle

Sugar (G3P, later glucose).

The Calvin cycle occurs where in the chloroplast

Stroma

Inputs of the Calvin cycle

CO₂, ATP, NADPH.

What is produced when water is split in photosynthesis.

Oxygen (O₂), electrons, protons

What problem does photorespiration cause

Oxygen competes with CO₂, reducing photosynthesis efficiency

What is the role of ATP in photosynthesis?

Provides energy for Calvin cycle reactions.

What are the two main stages of photosynthesis?

Light reactions and Calvin cycle.

What happens in Photosystem II (PSII)?

Water is split, electrons are excited by light, O₂ released.

What is photophosphorylation?

ATP production using light energy in the thylakoid

What is carbon fixation?

Incorporating CO₂ into organic molecules in the Calvin cycle.

What is RuBP?

A 5-carbon sugar that binds CO₂ in the Calvin cycle.

The enzyme that fixes carbon in the Calvin cycle.

Rubisco

First stable product of the Calvin cycle

3-PGA (3-phosphoglycerate).

Molecule directly produced by the Calvin cycle before glucose.

G3P

Where does the oxygen we breathe come from in photosynthesis?

Splitting water in the light reactions

What is chemiosmosis in photosynthesis?

Flow of H⁺ through ATP synthase to make ATP.

How are mitochondria and chloroplasts similar?

Both have double membranes, DNA, ribosomes, and make ATP

Wavelength with most energy

Violet/blue (shortest wavelength)

How many turns of the Calvin cycle are required to make one glucose?

6 turns

Role of DNA in the cell

It stores genetic information as a polymer

What is the cytoskeleton and what does it do?

A network of proteins that gives shape and moves materials

What structures do plant cells have that animal cells lack?

Cell walls and chloroplasts

What molecules cross membranes most easily?

Small and nonpolar molecules

Why are there 64 codons for only 20 amino acids?

redundancy of codons

How many amino acids are in a polypeptide when a stop codon is inserted early?

Fewer than normal (short polypeptide)

Can two mRNAs code the same protein with different codons? How?

Yes, because of redundancy (synonymous codons)

How is tRNA like a truck?

It delivers amino acids to the ribosome

Function of ribosomes

Read mRNA and build proteins by linking amino acids

What is aminoacyl-tRNA synthetase?

Enzyme that attaches amino acids to tRNAs

Why is protein synthesis energy demanding?

Many steps require ATP/GTP (charging tRNAs, peptide bonds, ribosome movement)