Cell Organelle Structures and Functions

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Questions and Answers

What is the primary direction of water movement in osmosis?

From an area of equal solute concentration to another equal concentration

From an area of high water concentration to low water concentration

From an area of high solute concentration to low solute concentration

From an area of low solute concentration to high solute concentration (correct)

During active transport, which condition must be met for the process to occur?

It can occur in either direction of the concentration gradient

It moves substances down the concentration gradient without energy

It requires ATP to transport substances against the concentration gradient (correct)

It only transports small uncharged particles

Where does transcription occur in the cell?

In the nucleus (correct)

In the mitochondria

In the rough endoplasmic reticulum

In the ribosomes

What is the end result of translation in protein synthesis?

Synthesis of a polypeptide chain Signup and view all the answers

In which part of the cell does glycolysis occur?

In the cytoplasm Signup and view all the answers

What is the net ATP gain from one molecule of glucose during cellular respiration?

30-32 ATP Signup and view all the answers

Which of the following best describes facilitated diffusion?

Passive transport of large hydrophilic substances via protein carriers Signup and view all the answers

What defines a hypertonic solution in relation to a cell?

Higher solute concentration outside the cell, causing water to exit the cell Signup and view all the answers

What molecule is primarily produced during cellular respiration that is used for energy in the cell?

ATP Signup and view all the answers

Which process allows plants to take in water through root hairs?

Osmosis Signup and view all the answers

What initiates osmosis in root hairs for water uptake?

Active transport of minerals Signup and view all the answers

What is the primary output of glycolysis?

ATP Signup and view all the answers

In which part of the cell does the Krebs cycle occur?

Matrix of mitochondria Signup and view all the answers

What is the total ATP produced during the electron transport chain per glucose molecule?

26 ATP Signup and view all the answers

Which of the following is a characteristic of active transport?

Moves molecules against the concentration gradient Signup and view all the answers

What role does the palisade mesophyll serve in a leaf?

Photosynthesis Signup and view all the answers

What is the main function of stomata in plants?

Gas exchange Signup and view all the answers

What substance acts as an electron donor in the electron transport chain?

NADH Signup and view all the answers

Which type of RNA is primarily involved in protein synthesis?

mRNA Signup and view all the answers

How do guard cells control the opening and closing of stomata?

By actively pumping potassium ions Signup and view all the answers

Which organelle is responsible for ATP production in cells?

Mitochondrion Signup and view all the answers

Which structure in the small intestine increases its absorptive surface area?

Microvilli Signup and view all the answers

In metabolic pathways, which process occurs in the mitochondrial inner membrane?

Electron Transport Chain Signup and view all the answers

Study Notes

Cell Organelle Structures and Roles

Nucleus protects and confines the genetic information (DNA) of the cell.
Ribosomes either float freely in the cytoplasm or are attached to the rough ER. They are the site of assembly of the building blocks to make proteins.
Chloroplast is the site of photosynthesis where light is captured, glucose & oxygen are made.
Rough Endoplasmic Reticulum (RER) has ribosomes on its surface, synthesizes & modifies proteins.
Smooth Endoplasmic Reticulum (SER) is the site of synthesis of lipids.
Golgi body is the site of protein sorting, packaging, and modification for use in the cell or export out.
Mitochondria is the site of aerobic cellular respiration, a reaction that produces the ATP.
Vacuole is for water and solute storage, also maintains plant cell structure.

Phospholipid Bilayer

Hydrophobic repels water, non-polar.
Hydrophilic attracts water, polar.

Material Transport Processes

Simple Diffusion
- Occurs in membranes and other areas.
- Movement is down the concentration gradient from high to low - passive.
- Uncharged particles like lipid-based substances and gases – hydrophobic only - can carry it out.
Facilitated Diffusion
- Requires a protein carrier in the membrane.
- Movement is down the concentration gradient from high to low - passive.
- Large hydrophilic substances can carry it out.
Osmosis
- Occurs in the phospholipids of the membrane.
- Movement is down the concentration gradient from high to low - passive.
- Water – hydrophilic - can carry it out.
- Definition: The passive movement of water across a semi-permeable membrane from an area of low solute (high water) concentration to an area of high solute (low water) concentration.
Active Transport
- Requires a protein channel.
- Movement is against the concentration gradient from low to high.
- Hydrophilic substances can carry it out.
- Definition: Requires ATP to move/pump ions (charged particles) against a concentration gradient from low to high concentration.

Solutions

Hypotonic Solution – water will move towards higher solute (low water), into the cell.
Hypertonic Solution – water moves towards higher solute (low water), outside the cell.
Isotonic – equilibrium of solute and solvent between inside and outside of the cell.

Protein Synthesis

Nucleotide – phosphate, sugar, base (A,C,T,G).
Ribosome – site of protein synthesis which occurs on its surface.
Transcription - DNA (A,C,T,G) template strand creates a single mRNA (A,C,U,G) strand in the nucleus using free nucleotides via RNA polymerase enzyme.
mRNA travels out of the nucleus to the ribosome.
Translation – tRNA brings an anticodon with an amino acid to the complementary mRNA codon which join together to create a polypeptide chain.
This amino acid sequence creates a specific protein.
Use of a genetic code table is necessary.

Cellular Respiration

Mitochondria
- Cristae - inner folds of the mitochondria.
- Matrix - the space within the inner membrane.
- Inner Mitochondrial Membrane - the membrane immediately surrounding the matrix.
- Outer Mitochondrial Membrane - the membrane that surrounds the whole mitochondrion.
Stages, Locations, and ATP Production
- Glycolysis
  - Location: Cytosol.
  - Net ATP Gain: 2.
  - Aerobic or Anaerobic: Anaerobic (no O2).
- Citric Acid Cycle / Krebs Cycle
  - Location: Matrix.
  - Net ATP Gain: 2.
  - Aerobic or Anaerobic: Aerobic. Doesn’t have O2 as an input, but is dependent on O2.
- Electron Transport Chain
  - Location: Cristae.
  - Net ATP Gain: 26.
  - Aerobic or Anaerobic: Aerobic. Literally has O2 as an input.
Glycolysis
- Location: Cytoplasm.
- Inputs: C6H12O6 (glucose), ADP + Pi.
- Outputs: Pyruvate, 2 ATP, H+ (from glucose).
Krebs Cycle
- Location: Matrix.
- Inputs: Pyruvate, O2, ADP + Pi.
- Outputs: CO2, 2 ATP, H+ (from pyruvate).
Electron Transport Chain
- Location: Inner mitochondrial membrane / Cristae.
- Inputs: H+, ADP + Pi, O2.
- Outputs: 6 ATP, H2O.

Photosynthesis

Purpose: To convert light energy into chemical energy (glucose) in the form of sugars.
When: Occurs in the presence of light.
Where: Occurs in chloroplasts.
Chloroplast – labelling
- Grana: Stacks of thylakoid membranes.
- Stroma: The fluid-filled region outside the grana.
Stages, Locations, Inputs, and Outputs
- Light-Dependent Reactions
  - Location: Grana.
  - Inputs: Light, H2O.
  - Outputs: O2, H+.
- Light-Independent Reactions
  - Location: Stroma.
  - Inputs: CO2, H+, ATP.
  - Outputs: C6H12O6 (glucose), H2O.

Digestive System

Chemical Digestion - Enzymes:
- Stomach: Pepsin action, optimal pH 2.
- Small Intestine: Trypsin action, optimal pH 8.
Small Intestine:
- Contains a specialized surface, with millions of tiny folds called villi, which increase its surface area.
- The epithelial cells lining the small intestine and its villi contain microvilli on their exposed surface, further increasing the surface area.
Macromolecules - Monomers
- Protein
  - Enzyme class required: Protease.
  - Monomer (absorbable): Amino acid.
- Carbohydrate
  - Enzyme class required: Amylases.
  - Monomer (absorbable): Monosaccharide, e.g., Glucose.
- Nucleic acid
  - Enzyme class required: Nuclease.
  - Monomer (absorbable): Nucleotide: nitrogen base and pentose sugar.

Plant Structure and Function

Leaf Structure
- Shape: Surface area to volume ratio is key for efficient photosynthesis.
- Cuticle: Waxy layer on the top surface, preventing water loss.
- Mesophyll: Two main layers:
  - Palisade mesophyll: Site of photosynthesis, located on the upper surface of the leaf.
  - Spongy mesophyll: Main site of gas exchange, located on the lower surface of the leaf.
- Stomata: Located on the underside of the leaf.
- Vascular bundles: Including xylem and phloem, located centrally for optimal access by all leaf cells.
Stomata Opening and Closing:
- Guard cells surround stomata and when they fill with water, the stomata open.
- When water is not available, the guard cells are not filled with water and the stomata close.
To close stomata and save water, plants:
- Actively pump potassium ions out of guard cells.
- Water then diffuses out of the vacuoles and guard cells.
- Each guard cell becomes flaccid, closing the stomata.

Water Movement

Root Structure:
- Shape: Root hairs increase surface area to volume ratio.
- Active transport of minerals: Initiates osmosis of water into root hairs.
Vascular Tissues
- Xylem:
  - Dead, continuous, unidirectional.
  - Moves water.
  - Cohesion/capillary action (water molecules sticking together) and adhesion (water molecules sticking to the sides of the vessel).
- Phloem:
  - Living, companion cells, bidirectional.
  - Moves sugar and minerals.

Key Knowledge: From Chromosomes to Genomes

Genes, Alleles, and Genome
- Gene: A section of DNA on a chromosome.
- Allele: An alternative form of a gene.
- Genome: The full set of DNA/genes in an organism.
Homologous Chromosomes
- Carry the same genes at the same gene loci, one from the mother, one from the father.
Autosomes and Sex Chromosomes
- Autosomes: Non-sex chromosomes, chromosome pairs 1-22.
- Sex chromosomes: X for female, Y for male.
Meiosis
- Produces haploid gametes from diploid cells.
- Involves two divisions:
  - Crossing over of chromatids.
  - Independent assortment of chromosomes.
- Key for creating genetic diversity.
Haploid and Diploid
- Haploid: 23 chromosomes in gametes (sperm and egg cells).
- Diploid: Full set, 46 chromosomes in all somatic cells (not gametes).

Genotypes and Phenotypes

Genotype: The genetic makeup of an organism.
- Use symbols to represent alleles at a particular gene locus, e.g., AA, Aa, aa.
Phenotype: The observable characteristics of an organism.
- Dominant and recessive phenotypes: Dominant alleles mask the expression of recessive alleles.
- Codominance: Both alleles are expressed equally, e.g., blood types (A, B, AB, O).
- Incomplete dominance: Neither allele fully dominates, resulting in a blended phenotype, (e.g., RR=Red, rr=White but Rr=Pink).
Epigenetic Factors
- Influence phenotypes by altering gene expression without changing the DNA sequence.
- These alterations may involve:
  - Changes in how tightly coiled DNA is around histones.
  - DNA methylation.

Patterns of Inheritance

Pedigree Charts: Maps used to track inheritance patterns within families.
Inheritance Patterns:
- Autosomal Dominant: Trait appears in every generation.
- Autosomal Recessive: Two unaffected parents can produce an affected child.
- Sex-Linked Dominant: More common in females; affected fathers pass the trait to all daughters, but not sons.
- Sex-Linked Recessive: More common in males; carrier females are often unaffected.
Monohybrid cross: A cross between two individuals that differ in one specific trait.
Monohybrid test cross: A cross between an individual with an unknown genotype for a particular trait and an individual with the homozygous recessive genotype for that trait.
- Purpose: To determine the genotype of the parent displaying the dominant phenotype.
- How it works: Cross the parent with an organism of known recessive phenotype.

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Description

This quiz explores the various cell organelles and their specific roles within the cell. It covers essential topics such as the nucleus, ribosomes, chloroplasts, and more. Test your understanding of how these structures contribute to cellular functions and overall biology.