Parts/functions of the cell and cell signaling/Structure of life

Eukaryotic cells

Eukaryotic cells

• larger

• contains DNA in nucleus

• name means true nucleus

• contains organelles

Prokaryotic cells

• smaller

• DNA is loose

• name means before nucleus

• no organelles

Similarities between eukaryotic and prokaryotic cells

• cytoplasm

• plasma membrane

Why would a cell want to have a higher surface area to volume ratio?

It’s faster to get things in and out of the plasma membrane

Which would have a higher surface area to volume ratio?

prokaryotic cell

eukaryotic

they are probably equal

prokaryotic cell

Cytoplasm

• interior of the cell

• filled with jelly-like cytosol

Endomembrane system

• continuous with the nuclear envelope

• intracellular network of membranes

What does the Endomembrane consist of?

nuclear envelope

endoplasmic reticulum

golgi apparatus

vesicles

Vesicles

• little pouches of plasma membrane

• functions

  • pinch off and float around to carry things

Chromatin

loosely wound DNA

Chromosome

tightly wound DNA

Nuclear Envelope

barrier that separates the contents of the nucleus from the cytosol

Nucleolus

makes ribosomal subunits from proteins and rRNA (ribosomal RNA)

Nuclear Pore

very small opening for small molecules to pass in and out of the nucleus

Ribosome

• made of rRNA and protein

• facilitates turning mRNA into protein

• not membrane bound so they are also found in prokaryotes

What is the main process that occurs in the nucleus?

• houses the DNA

• copies DNA

Endoplasmic Reticulum (C & BC)

Network of membranous sacs and tubules

cisternae

Smooth ER (C)

• lipid synthesis

• detox

• calcium storage

Rough ER (BC)

• factory for protein creation (has lots of ribosomes)

• manufactures membrane

Golgi apparatus (E)

• shipping and receiving

• can also manufacture polysaccharides

Lysosomes (BD)

Sacs of digestive enzymes

What is phagocytosis?

Cell eating

What is autophagy?

self eating

• helps recycle cell components

Vacuoles (C)

• large vesicle

• big compartment

1. nucleus

2. endoplasmic reticulum

3. vesicles

4. golgi apparatus

5. vesicles

Which order of organelles would you expect a protein to be involved with during its production until it’s ready to do its job (from instruction to final product)?

Mitochondria (A)

• powerhouse of the cell

• harness energy

• cellular respiration

  • uses oxygen + fuel from food = ATP

Chloroplasts (B)

• harness energy from the sun to synthesize carbohydrates

• only found in plants

• contains chlorophyll (green pigment)

What is the endosymbiont theory?

Theory that the mitochondria and chloroplasts were the primitive cells engulfed and developed into the cells we see today.

Evidence

• double membraned unlike other organelles

• they have their own DNA

  • main DNA in nucleus carries vast bulk of the cell info

Mitochondria and chloroplasts have their own DNA

Endosymbiont theory is supported by which of the following?

Mitochondria and chloroplasts have their own DNA

Mitochondria can consume other organelles

Thylakoids have smaller mitochondria inside them

The cell wall of plants had to arise to keep engulfed organisms inside

All of the above

Cytoskeleton

internal scaffolding and movement

1. microtubules

2. intermediate filaments

3. microfilaments

What are the 3 types of components in the cytoskeleton?

Microtubules

• hollow

• made of tubulin (protein)

• important in movement and structure

• can be “tracks” for motor proteins

• some originate from centrosome (not all … come from centrosomes)

• separate the chromosomes during cell dividing

• control the movement of cilia and flagella

What are the functions of microtubules?

Flagella: long undulating tail

Cilia: lots and lots of shorter mini-oars

What are flagella and cilia?

• 9+3 basal body

• 9+2 extended portion

How are microtubules arranged?

Intermediate filaments

• twisted fibrous proteins (can be several types of proteins

• function - anchor (holds things) and structure

Microfilaments

• made of actin (protein)

• functions: muscle contraction, cytoplasmic streaming, cell shape

microtubules

If a drug disrupts the ability of the cell to move chromosomes during cell division, which structure would it likely be targeting?

What do plants and prokaryotes have that animal cells don’t?

cell wall

• made out of cellulose

• sturdy

• standing upright because it has enough water

What is turgor?

• bent over structure

• happens because it lost too much water

What is wilting?

Extracellular matrix

• in animal cells

  • complex protein and carbohydrates outside of the cell

• tight junction

• desmosome

• gap

• plasmodesmata (only in plants)

What are the 4 types of junctions?

• prevents cells from leaking (cell to cell)

• A

What are tight junctions?

• rivets

  • acts as molecular velcro

• prevents cells from ripping apart

• B

What is desmosome?

• channel

• facilitates fast communication

C

What are gap junctions?

• cell wall channels for plants

• cytosol, water, and ions pass through

What is plasmodesmata?

gap junctions and desmosomes

Which types of cell junctions would you expect to find in a tissue that undergoes both high mechanical stress and needs to facilitate rapid, coordinated signaling?

Plasma membrane

• separates intracellular from extracellular

• selective permeable (blocks some movement and facilitates others with channels & receptors)

  • allows control

Membrane proteins

• allows communication with extracellular environment

• most specialized membrane functions

• some tethered to intracellular structures

Integral: embedded

Peripheral: loosely bounded

What are the 2 types of membrane proteins?

1. transport channels

2. receptors for signal transduction

3. cytoskeleton attachment

4. enzymatic activity

5. intercellular attachment (cellular adhesion molecules)

6. cell-cell recognition

What are the 6 membrane protein functions?

Amphipathic

What is the word for something that is part hydrophilic and part hydrophobic (phospholipids)?

the polar heads face the interior and exterior of the cell with the tails forming the center of the membrane

Phospholipids orient themselves in aqueous solution such that _____.

• it reduces fluidity at moderate temperatures

• at cold temperatures it hinders solidification

What does cholesterol do when it’s in the membrane?

• an ice dwelling fish

The plasma membrane shouldn’t be too rigid or too fluid. The cold would make the membrane solidify, but with more cholesterol it would make the membrane more fluid and offset the cold.

Which would have higher unsaturated fatty acids in its plasma membrane and why?

• primary

• secondary (co-transporters)

• vesicular

  • exocytosis

  • endocytosis

    • phagocytosis (cell eating)

    • pinocytosis (drinking)

    • receptor-mediated endocytosis

What are types of active transport?

• diffusion

  • simple

  • facilitated

    • carrier mediated

    • channel mediated

    • aquaporins - part of osmosis

What are types of passive transport?

substances will move until they are equally distributed with no energy required

What is diffusion?

From high to low concentration

How does the solute move in simple diffusion?

Osmolarity

• concentration metric

• # of molecules per volume fluid

Osmosis

• movement of H2O to equalize the osmolarity

  • if a solute can’t pass, and water can, water will move across

Tonicity

ability of solution to alter cell’s water volume

Hypertonic

more solutes in a solution than cell

Isotonic

same solutes in solution as cell

Hypotonic

less solutes in solution than cell

Aquaporins

a channel specifically for H2O

• speeds up the movement of H2O

Channel mediated diffusion

channel for molecules (specific to charge & size)

• ion gated (ion has to be bounded for it to open)

• voltage gated (closed until right electric voltage hits it)

Carrier mediated diffusion

physically moves large molecules

gain; osmosis

A red blood cell placed into a container of distilled water (that has, no solute molecules) will ____ water via _____

Primary transport only carry substances against the concentration gradient.

In secondary transport, primary transport goes against making the concentration change.

As a result, certain substances can diffuse down the concentration gradient.

What is the difference between primary and secondary transport?

Primary transport example

sodium-potassium pump

active transport

Is primary and secondary transport active or passive?

Secondary transport example

• sodium-glucose cotransporter

They are signals that travel short distances to initiate a response.

• gap junctions

• cell-cell recognition

• paracine: local regulator (synaptic)

What is local signaling?

Signals that travel through your entire body or more than half of your body to initiate a response.

• endocrine

• nervous tissue

What is long distance signaling?

nervous systems

Which of the following involves both electrical and chemical signals?

a. paracrine signals

b. local regulators

c. nervous systems

d. endocrine

1. reception

2. transduction

3. response

What are the 3 stages of cell signaling?

Reception

recognizing the signaling molecule

Transduction

covering the signal into a form that can trigger a cellular response

• often involves relay molecules

Response

finally triggers the specific activity

• Ex: breaks down glycogen or activates a specific gene

1. Plasma membrane receptors

2. Intracellular receptors

What are the 2 options for receptors?

a signaling molecule that binds specifically to another molecule

What is a ligand?

• G-protein coupled receptor

• ligand gated ion channel

What are examples of plasma membrane receptors?

• utilizes a transmembrane receptor

• binds GTP (energy shuttle molecule similar to ATP)

• activates another enzyme

What does a G-protein coupled receptor do?

• channel only opens when a specific ligand binds

  • allows movement of molecules that may trigger an intracellular response

What does a ligand gated ion channel do?

• lipid soluble signals that can diffuse through the plasma membrane

  • steroids

What are intracellular receptors?

c. intracellular, because the receptor is located within the cell

The figure represents which of the following types of receptor and how do you know?

a. intracellular, because the signal is getting inside the cell

b. ligand gated ion channel because ligands are binding

c. intracellular, because the receptor is located within the cell

d. G-protein, because GTP is dropped off inside the cell

• protein kinase

• protein phosphatase

What are the two actions in the phosphorylation cascade?

It’s when a phosphate group is transferred, then it phosphorylates, and that activates a response.

What is protein kinase?

It’s when a phosphate group is removed and the response is deactivated

What is a protein phosphatase?

Amplification

What does transduction (phosphorylation cascade) result in?

e. both c and d

Where would you expect to find second messengers during signal transduction?

a. in the extracellular matrix

b. attached to DNA

c. in the transduction phase

d. activating protein kinases

e. both c and d

d. estrogen binds to specific receptors inside many kinds of cells, each of which has different response to its binding

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?

a. estrogen is produced in high concentrations by a large number of different cell types

b. estrogen binds to common receptors inside several cell types, and each cell responds in the same way to its binding

c. estrogen does not affect cells that lack estrogen receptors in the cell membrane

d. estrogen binds to specific receptors inside many kinds of cells, each of which has different response to its binding

all chemical reactions in an organism

What is metabolism?

build up

ex: dehydration reaction

What is an anabolic reaction?

break down

ex: hydrolysis

What is a catabolic reaction?

motion energy

What is kinetic energy?

kinetic energy associated with random movement of atoms or molecules

ex: heat

What is thermal energy?

energy that matter possesses because of their location or structure

What is potential energy?