Cellular Neuro Exam 1

Multipolar Neuron

Function: Motor + integration
Structure: Many dendrites, 1 axon

Bipolar Neuron

Function: Special senses
Structure: 1 dendrite, 1 axon

Pseudounipolar Neuron

Function: Sensory
Structure: 1 process that splits

Pyramidal Neuron

Function: Excitatory signaling
Location: Cerebral cortex

Purkinje Neuron

Function: Inhibitory signaling
Location: Cerebellum

What are the pros & cons of one neuron reaching many cells (divergence)?

✅ Pro: spreads/coordinates a signal widely
❌ Con: less specific control

How does enzyme speed differ for classical vs. non-classical neurotransmitters?

Classical NTs → slower enzymes → needed all the time
Non-classical NTs → faster enzymes → made when needed

which neurons would you expect to receive more information

multipolar

Which two organelles have higher calcium stores when compared to cytosolic levels

mitochondria and ER

what does mitochondria generate

ATP

Electrical signals are

Faster

vesciles are

presynaptic

How are neurons similar to other cells?

membrane + cytoplasm (cytosol + organelles)

What makes up a neuron’s cytoplasm?

Cytosol + membranous organelles

Cytosol includes the cytoskeletal matrix.

hat are the major organelles in the neuronal cell body?

Nucleus → ER → Golgi → vesicles + lysosomes/endosomes

What is the secretory/transport pathway in a neuron?

ER → cis-Golgi → Golgi stacks → trans-Golgi → vesicles

How do materials get from the neuronal cell body to the synaptic terminal?

transport vesicles travel down the axon → synaptic terminal

What is the endosome/lysosome pathway shown in the diagram?

Early endosome → late endosome → lysosome

Organelle

A specialized structure inside a cell that has a particular job

Cell membrane

Outer boundary of the cell; controls what enters/leaves

Cytoplasm

Everything inside the cell membrane except the nucleus

Cytosol

The fluid portion of the cytoplasm

ER (endoplasmic reticulum)

Membrane network inside the cell that helps make/process molecules

Ribosome

Tiny structure that builds proteins

Lysosome

Breaks down/recycles cellular material

Cytoskeleton

Internal protein framework that gives the cell structure + transport tracks

Synaptic vesicle

Tiny sac containing neurotransmitter

What are the major parts of a neuron, and what direction does information generally travel?

Dendrites → Cell body (soma) → Axon → Synapses

• Dendrites = receive input

• Soma = main cell body

• Axon = carries signal away

• Synapse = communication point with another cell

Apical dendrite

large dendrite extending from the top of the soma

Apical tuft

branches at the top/end of the apical dendrite

Basal dendrites

dendrites extending around the base of the soma

What is the axon hillock?

The region where the axon begins at the soma.

genome vs chromosome

• Genome = all of a cell’s DNA

• Chromosomes = packaged DNA

What is transcription?

Making an mRNA copy of a gene

DNA → mRNA

How does information in DNA ultimately become a protein?

DNA → mRNA → Protein

1. Transcription: DNA → mRNA (nucleus)

2. mRNA leaves the nucleus

3. Translation: mRNA → protein (cytoplasm)

What is mRNA, and what does it do?

It carries the information from:

Nucleus → cytoplasm → protein production

What does the nucleolus do?

Makes rRNA (ribosomal RNA).

rRNA

an important part of ribosomes, which make proteins.

2 types of ER

Rough ER → proteins
Smooth ER → lipids + Ca²⁺

What does the rough ER (RER) do, and why is it “rough”?

Makes proteins and works with the Golgi to send them where they need to go.

Looks rough because it is covered in ribosomes.

What does the smooth ER (SER) do?

1. Makes lipids + steroids
2. Metabolizes carbohydrates + steroids
3. Regulates Ca²⁺ concentration

🧠 Smooth = Lipids + Metabolism + Ca²⁺

L-M-C

How can you visually tell rough ER vs. smooth ER apart?

Rough ER: has ribosomes (dots) on it
Smooth ER: no ribosomes=

What does the Golgi do?

Modifies, packages, and sends proteins.

What are the 2 sides of the Golgi?

Cis = receives
Trans = sends

Cis comes in → Trans travels out

What does the Golgi often add to proteins/lipids?

• Sugar + protein = glycoprotein

• Sugar + lipid = glycolipid

What is the main job of the mitochondria?

Makes ATP (energy) ⚡

What else do mitochondria help with?

Proteins + Ca²⁺ regulation + cell signaling

Where is Ca²⁺ (calcium) stored inside neurons?

ER + mitochondria

What does calcium (Ca²⁺) help control in neurons?

• Cell signaling

• Ion channels

• Gene expression

How do the ER and mitochondria differ in handling Ca²⁺?

ER = releases stored Ca²⁺
Mitochondria = slow Ca²⁺ buffer

What is the cytoskeleton?

The cell's internal support framework + transport system.

What are the 3 main parts of the cytoskeleton?

• Actin filaments

• Microtubules

• Intermediate filaments

What are actin filaments?

The smallest cytoskeleton fibers.

Help with:

• Cell movement

• Cell division

• Growing axons/dendrites

What are intermediate filaments called in neurons?

Neurofilaments

Main job = strength/support

What are microtubules?

Hollow tubes that act as tracks for transport inside neurons.

− end →

toward nucleus

+ end →

away from nucleus

What is anterograde vs. retrograde axonal transport?

Anterograde: soma → axon terminal
Retrograde: axon terminal → soma

Which motor proteins move along microtubules?

Kinesin → + end → AWAY from nucleus
Dynein → − end → TOWARD nucleus

Kinesin

OUT / anterograde

Dynein

IN / retrograde

What is the cell membrane made of?

A phospholipid bilayer = 2 layers

How are phospholipids arranged in the membrane?

Heads → face water 💧
Tails → hide from water

polarity with heads and tails

• Heads = polar

• Tails = nonpolar/hydrophobic

What can easily cross the phospholipid bilayer?

Small, nonpolar molecules

Examples: O₂ and CO₂

What are the 3 main types of transmembrane proteins?

Carriers → carry
Channels → passageways
Receptors → receive signals

What do carrier proteins do?

Bind a molecule and carry it across the membrane by changing shape.

What do channel proteins do?

Form tunnels through the membrane.

Allows specific molecules/ions to pass.

What do receptor proteins do?

Receive chemical signals outside the cell → cause a response inside.

How does a receptor turn an outside signal into an inside response?

Signal binds outside → receptor changes → signal is passed inside

What can happen to a signal after a receptor receives it?

• Relayed → passed onward

• Amplified → made stronger

• Integrated → combined with another pathway

What are the 2 major types of gated ion channels?

• Ligand-gated → opens when a chemical binds

• Voltage-gated → opens when voltage changes

Why are ion channels important?

control ion movement → neuron signaling.

What does the sodium-potassium pump do?

Uses ATP (energy) to pump:

3 Na⁺ OUT
2 K⁺ IN

Why is the Na⁺/K⁺ pump called active transport?

Because it requires energy (ATP) to move ions across the membrane.

How does an electrical signal travel within a neuron?

By a change in voltage across the cell membrane ⚡

How does a chemical synapse send a message?

Synaptic vesicles release neurotransmitter → neurotransmitter binds receptors on the next neuron.

What is a dendritic spine?

A small bump on a dendrite where synapses commonly form.

PRE = vesicles →

SENDS neurotransmitter

POST = receptors

→ RECEIVES neurotransmitter

hat do the different dendritic spine shapes mean?

• Thin → weaker synaptic transmission → LTD

• Stubby/mushroom → stronger synaptic transmission → LTP

What are LTP vs. LTD?

• LTP = synapse gets stronger

• LTD = synapse gets weaker

What does a gene produce?

A functional product, often a protein.

What are the 3 steps of translation?

Initiation → Elongation → Termination

What happens during translation?

Ribosome reads mRNA → joins amino acids → protein

What is transcription vs. translation?

Transcription: DNA → mRNA (copy)
Translation: mRNA → protein (build)

What do mRNA and tRNA do during translation?

mRNA = instructions 📖
tRNA = brings amino acids 🧱

Ribosome reads mRNA and connects the amino acids → protein

What are the 2 parts of a ribosome?

Small subunit → binds mRNA
Large subunit → works with tRNA + amino acids

Free vs. membrane-bound ribosomes make proteins for where?

Free ribosomes → proteins used INSIDE the cell

ER-bound ribosomes → proteins sent to membranes/organelles or OUT of the cell

What is the Central Dogma?

DNA → mRNA → Protein

Transcription

DNA → mRNA

Translation

mRNA → protein

DNA —Transcribe→

RNA —Translate→ Protein

What happens during translation, and what are its major stages?

During translation, the information encoded in mRNA is used to construct a protein, a large molecule consisting of one or more long chains of amino acid residues.

Translation has 3 major stages:

1. Initiation

2. Elongation

3. Termination

How does translation occur?

• Ribosome binds mRNA

• tRNA brings amino acids + binds mRNA

• Ribosome moves along mRNA

• Amino acids join → growing peptide chain

what does tRNA do?

Carries an amino acid → ribosome and binds the mRNA.

After delivery → empty tRNA exits.

What do the 2 ribosomal subunits do?

• Small → binds mRNA

• Large → binds tRNA + amino acids

What do free ribosomes do?

• Move freely in cytosol

• Make proteins released into cytosol

• Proteins are used within the cell

• What do membrane-bound ribosomes do?

• Bound to rough ER

• Make proteins for organelles or exocytosis (e.g., transmitters)

• New protein enters ER → secretory pathway → destination

Which scientist was champion for what theory