Cell Bio EX 1

One idea of life is that early Earth had conditions that allowed

simple inorganic molecules to form organic molecules.

What is the Miller-Urey Experiment

tested whether organic molecules could form under conditions thought to resemble early Earth

What was the result of the Miller-Urey Experiment

did NOT create life. It demonstrated that some molecules necessary for life can form naturally under certain conditions.

What are the 3 major doctrines of cell theory

• All living organisms are composed of one or more cells.

• The cell is the basic unit of life.

• All cells come from pre-existing cells.

What are the differences in Prokaryotic and Eukaryotic cells

Feature	Prokaryotic	Eukaryotic
Nucleus	❌ No	✅ Yes
Membrane-bound organelles	❌ No	✅ Yes
DNA location	Nucleoid	Nucleus
Size	Generally smaller	Generally larger
Examples	Bacteria, Archaea	Animals, plants, fungi, protists
Ribosomes	Yes	Yes
Plasma membrane	Yes	Yes

What are the similarities in Prokaryotic and Eukaryotic cells

• DNA

• Ribosomes

• Cytoplasm

• Plasma membrane

What is cell differentiation

The process by which unspecialized cells become specialized cells.

Examples:

• Muscle cells

• Neurons

• Skin cells

• Red blood cells

What are somatic cells

Somatic cells = all body cells except germ cells.

Examples:

• Muscle cells

• Liver cells

• Skin cells

• Neurons

Why are cells small

the importance of the surface-area-to-volume ratio.

allowing more efficient exchange with the environment.

What is diffusion

The movement of molecules from an area of higher concentration → lower concentration.

What does metabolism require

• Nutrients entering

• Oxygen entering

• CO₂ leaving

• Waste products leaving

What is resolution

ability to distinguish two objects as separate

Higher resolution = more detail.

What is magnification

Makes an object appear larger.

What is Numerical Aperture

Numerical aperture describes the ability of a microscope objective to collect light and resolve fine detail.

What is TEM (Transmission Electron Microscopy)

• Electrons pass through specimen

• Shows internal structures

• Very high resolution

What is SEM (Scanning Electron Microscopy)

• Scans surface

• Gives detailed surface appearance

• Often appears three-dimensional

What is the process of Fluorescence microscopy

Excitation light → fluorophore absorbs energy → emits light → image

What is confocal microscopy

• Uses a focused laser

• Collects light from a specific focal plane

• Uses a pinhole to reject out-of-focus light

• Can create optical sections

• Can reconstruct 3D structures

What is immunocytochemistry

Uses antibodies to identify specific proteins within cells.

Antibody → binds specific antigen/protein → label produces detectable signal

What is a molecular beacon

a fluorescent probe used to detect a specific nucleic acid sequence.

It typically has a hairpin structure.

When a target is absent in fluorescence

The probe is closed → fluorescence is quenched.

When target is present:

The probe binds its complementary sequence → hairpin opens → fluorescence becomes detectable.

When the Target DNA/RNA opens the beacon →

fluorescence turns on.

What are the main components of the plasma membrane

Main components

• phospholipids

• proteins

• cholesterol

• carbohydrates

What are the membrane proteins of the plasma membrane

• integral

• peripheral

What are phospholipids function in the plasma membrane

• Form bilayer

• Hydrophilic heads face water

• Hydrophobic tails face inward

What are proteins function in the plasma membrane

• Transport

• Signaling

• Enzymatic activity

• Cell adhesion

What is cholesterol’s function in the plasma membrane

Helps regulate membrane fluidity

What is carbohydrates’ function in the plasma membrane

• Important for cell recognition and communication

• Often attached to proteins/lipids on the extracellular surface

What are integral proteins

• Embedded in membrane

• Many span the entire bilayer

What are peripheral proteins

Associated with membrane surface

What do cilia have

a 9 + 2 microtubule arrangement.

Movement is powered by dynein using ATP.

What is the main function of the golgi apparatus

Modifies, sorts, packages proteins/lipids

What is the main function of the lysosome

Membrane-bound organelles containing digestive enzymes.

Break down:

• Macromolecules

• Damaged organelles

• Cellular debris

• Material taken into the cell

What is the main function of peroxisome

Fatty acid oxidation/detoxification

What is the main function of the proteasome

Break down individual unwanted/damaged proteins.

Usually proteins are tagged with ubiquitin before degradation.

What are the 4 steps of protein synthesis

Step 1 — Transcription

Occurs in the nucleus.

DNA → mRNA

Step 2 — Translation

Occurs at ribosomes.

mRNA → protein

Step 3 — Processing

Proteins may be modified in the:

• ER

• Golgi

Step 4 — Trafficking

Proteins are transported in vesicles to their destinations.

What are the differences between Rough ER and Smooth ER

Rough ER	Smooth ER
Has ribosomes	No ribosomes
Protein synthesis	Lipid synthesis
Processes proteins	Detoxification
Produces proteins for secretion/membranes	Ca²⁺ storage
Part of secretory pathway	Important in steroid-producing cells

What is the pathway for cell signaling

Signal → receptor → transduction → responses

What are the different types of receptors

cell surface receptors

intracellular receptors

What are Cell-surface receptors

Used for signals that cannot easily cross the plasma membrane.

What are Intracellular receptors

Used by signals that can cross the membrane, often lipid-soluble molecules.

Example:

• Steroid hormones

What happens during the transduction step in cell signaling pathway

The signal is converted into an intracellular response.

May involve:

• Protein phosphorylation

• Second messengers

• Protein interactions

• Ion channels

What happens during the response step in cell signaling pathway

The cell changes its behavior.

Examples:

• Gene expression

• Metabolism

• Cell division

• Movement

What is amplification

One ligand-receptor interaction can trigger a cascade involving many molecules.

What is Cell adhesion

Cells attach to:

• Other cells

• Extracellular matrix (ECM)

Important adhesion proteins include cadherins and integrins.

What is the extracellular matrix

Material outside cells that provides:

• Structural support

• Cell attachment

• Signaling

• Tissue organization

What is determination

A cell becomes committed to a particular developmental pathway.

What is differentiation

The cell develops specialized characteristics and functions.

What are cytoplasmic determinants

molecules in the cytoplasm of an egg that influence cell development.

These can include:

• mRNAs

• Proteins

• Regulatory molecules

What are genetic factors

• Gene expression

• Transcription factors

• Signaling pathways

• Cytoplasmic determinants

Genes provide developmental instructions, but environmental conditions can

influence how those instructions are expressed.

What are stem cells

• Self-renewal

• Differentiation

What is totipotent

Can produce all cell types, including extraembryonic tissues.

What is pluripotent

Can produce many/all body cell types but not an entire organism.

What is multipotent

• Can produce multiple related cell types.

What are the steps of SCNT

• Take nucleus from a somatic cell.

• Remove nucleus from an egg cell.

• Insert somatic nucleus into enucleated egg.

• Stimulate cell to divide.

• Develop an embryo.

What is therapeutic cloning

SCNT can potentially produce embryonic stem cells genetically matched to the nuclear donor for research or potential therapeutic purposes.

Where does glycolysis occur

cytosol

What does glucose turn into in glycolysis

2 pyruvate

Glycolysis occurs in 2 phases, what are they called

Energy investment phase

• ATP is consumed.

Energy payoff phase

• ATP and NADH are produced.

What is the first key step in glycolysis

1. Hexokinase

Glucose + ATP → glucose-6-P (G6P) + ADP

What is the second key step in glycolysis

2. Phosphofructokinase-1 (PFK-1)

Fructose-6-phosphate → Fructose-1,6-bisphosphate

⭐ Major rate-limiting/regulatory step of glycolysis

What is the third key step in glycolysis

Glyceraldehyde-3-phosphate dehydrogenase

Produces NADH.

What is the fourth key step in glycolysis

4. Pyruvate kinase

Phosphoenolpyruvate → Pyruvate

Produces ATP.

What is major regulatory enzyme in glycolysis

PFK-1

High ATP → inhibits glycolysis

Low energy/AMP → stimulates glycolysis

What is net glycolysis output per glucose

2 ATP + 2 NADH + 2 pyruvate

What is pyruvate oxidation

Occurs in the mitochondrial matrix in eukaryotic cells.

Each pyruvate becomes:

Acetyl-CoA + CO₂ + NADH

What is the main purpose citric acid cycle

producing NADH and FADH₂, which carry electrons to the electron transport system.

Therefore, the cycle runs twice per glucose.

What are the 4 major somatic tissue types

• epithelial tissue

• connective tissue

• muscle tissue

• nervous tissue

What is epithelial tissue

Covers surfaces and lines cavities.

Functions:

• Protection

• Absorption

• Secretion

• Transport

Examples:

• Skin

• Intestinal lining

What is connective tissue

Supports, connects, and protects.

Examples:

• Bone

• Cartilage

• Blood

• Adipose

• Tendons

What is muscle tissue

Produces movement through contraction.

Three types:

• Skeletal

• Cardiac

• Smooth

What is nervous tissue

Responsible for:

• Communication

• Electrical signaling

• Coordination

Main cells:

• Neurons

• Glial cells

What is CNS

Brain + spinal cord

What is PNS

All neural tissue outside the brain and spinal cord.

Includes:

• Nerves

• Ganglia

What is action potential

a rapid change in membrane potential that allows neurons to communicate.

What are the steps in action potential

1. threshold

2. depolarization

3. peak

4. repolarization

5. hyperpolarization

6. return to resting potential

What is the threshold step in action potential

A stimulus depolarizes the membrane.

If threshold is reached:

Action potential begins.

What is the depolarization step in action potential

Voltage-gated Na⁺ channels open.

Na⁺ enters the neuron.

Membrane becomes more positive.

What is the peak step in action potential

Na⁺ channels become inactivated.

The membrane reaches a positive voltage.

What is the repolarization step

Voltage-gated K⁺ channels open.

K⁺ leaves the cell.

Membrane becomes negative again.

What is the hyperpolarization step

K⁺ channels remain open slightly too long.

Membrane becomes more negative than resting potential.

What is the return to resting potential step

Ion channels return to their resting states and ion gradients are maintained/restored.

What are the steps of how everything is connected

1. glycolysis

   1. Glucose → Pyruvate

2. pyruvate oxidation

   1. Pyruvate → Acetyl-CoA

3. Citric Acid Cycle

   1. Acetyl-CoA → NADH + FADH₂

4. ETS

   1. NADH/FADH₂ → H⁺ gradient

5. ATP synthase

   1. H⁺ gradient → ATP

What happens to the electrons in the ETC

Electrons move through a series of protein complexes.

As electrons move through the ETS, energy is released.

That energy is used to pump: H⁺ (protons)

What is chemiosmosis

The H⁺ wants to move back into the matrix.

it goes through: ATP SYNTHASE

As H⁺ flows through it:

ADP + Pi → ATP

What is oxidative phosphorylation

1. Electron transport

Electrons move through the ETS.

2. Chemiosmosis

The H⁺ gradient powers ATP synthase to make ATP.

Why is oxygen important in OXIDATIVE PHOSPHORYLATION

Without oxygen, the electrons can't continue flowing through the normal aerobic ETS

No oxygen → ETS stops → proton gradient collapses → oxidative phosphorylation stops

What is the summary of ATP production

2 from glycolysis

4 from NADH generated in glycolysis

2 from citric acid cycle (through GTP)

28 from ETS

36 molecules total

What are the key steps in the citric acid cycle

• Breaks down 2 pyruvic acid molecules

• Produces 2 ATP by way of GTP

• Transfers H atoms to NADH and FADH2

• Coenzymes provide electrons to ETS

What are the key steps of ETS

• Each of eight NADH molecules
• Produces 3 ATP + 1 water molecule
• Each of two FADH2 molecules
• Produces 2 ATP + 1 water molecule
• Total yield from citric acid cycle to ETS
• 28 ATP

What is a ligand

A ligand is a molecule that binds to a receptor.

What are the 4 types of cell signaling

endocrine

paracrine

autocrine

synaptic

What is endocrine signaling

Signals travel through the bloodstream to distant cells.

Example:

Insulin

What is paracrine signaling

Signals act on nearby cells.

Example:
Growth factors released by one cell affect neighboring cells.

What is autocrine signaling

A cell releases a signal that acts on the same cell that released it.

What is synaptic signaling

Neurons release neurotransmitters across a synapse.

The signal travels a very short distance but is highly specific.

What are G-Protein-Coupled Receptors (GPCRs)

a large protein on the surface of a cell that detects signals from outside the cell and triggers internal cellular responses