Intro to the Cell

Question 1

What is the Cell theory?
Hint (there are 3)

Answer 1

1. All living organisms are composed of one or more cells
2. The cell is the basic unit of structure and organisation
3. All cells arise only from pre-existing cells

Question 2

What are Universal similarities between cells?
Hint (there are 3)

Answer 2

1. DNA as the heritable material, RNA as a messenger and proteins as the workers
2. Major cellular organelles - functions and arrangements within the cell
3. ATP as an energy source

Question 3

What is The Central Dogma?

Answer 3

DNA-> RNA ->PROTEIN

Question 4

What are the similarities between Prokaryote cell versus eukaryote cell?

Answer 4

Both have:
Plasma membrane, cytosol, DNA, RNA, protein and ribosomes

Question 5

What are the differences between Prokaryote cell versus eukaryote cell?

Answer 5

Eukaryotic cells have membrane-bound organelles and are much larger

Prokaryote cells lack a membrane-bound nucleus

Question 6

What is included in the cytoplasm?

Answer 6

The cytoplasm is everything inside the plasma membrane including the organelles, but not including the nucleus

Question 7

What is the cytosol?

Answer 7

The fluid portion of the cytoplasm is the cytosol

Question 8

What is the cytosol made up of?

Answer 8

water plus dissolved and suspended substances (eg. ions, ATP, proteins, lipids)

Question 9

What organelles are part of the endomembrane system?

Answer 9

Nucleus
Endoplasmic Reticulum (smooth and rough)
Golgi apparatus
Lysosomes

Question 10

Which two organelles are not part of the endomembrane system?

Answer 10

Mitochondia
Ribosomes

Question 11

What is the the endomembrane system function?

Answer 11

along with plasma membrane, they work together to package, label and ship molecules)

Question 12

The plasma membrane is selectivley permearble, what does that mean?

Answer 12

The plasma membrane is a selectively permeable barrier controlling
the passage of substances in and out of the cell

Question 13

What does the Plasma membrane consist of?

Answer 13

double layer of phospholipids with embedded proteins

Physical barrier separating the inside / outside of cell

Question 14

What is hydrophillic & hydrophobic

Answer 14

phobic- doesnt like water-fats
phillic- does- majority of our body

Question 15

WHat do the fats in the cell membrane do?

Answer 15

provide a barrier to water

Question 16

What is a phospholipid?

Answer 16

hydrophilic polar heads (phosphate)
* hydrophobic lipid tails (fatty acids)
* arranged as a double layer around cytoplasm, tail to tail

Question 17

What do Plasma Membrane proteins do?

Answer 17

mediate movement of hydrophilic substances

allow cell-cell identification and facilitate intercellular communication

Question 18

What does amphipathic mean?

Answer 18

they have both hydrophilic and hydrophobic regions

Question 19

What are Integral proteins?

Answer 19

embedded (partially or fully) into the membrane
eg. Transmembrane proteins are integral membrane
proteins that fully span the entire membrane,
contacting both extracellular and cytoplasmic areas

Question 20

What are Peripheral membrane proteins?

Answer 20

associated with the membrane, but not actually
embedded in it

Question 21

Transport protein?

Answer 21

For example, channels,
transporters, may be
general or selective,
gated or not

Question 22

Enzyme activity proteins

Answer 22

Carry out chemical reaction,
may or may not be a part of a
team of enzymes

Question 23

Signal transduction protein

Answer 23

External signaling molecule
causing communication of
information to the inside of the
cell

Question 24

cell-cell recognition protein

Answer 24

Use of glycoproteins
(carbohydrate + protein) as
molecular signatures of the
extracellular side of the cell

Question 25

Intercellular joining protein

Answer 25

For example, gap junctions or tight junctions

Question 26

Attachment to ecm/cytoskelten protein

Answer 26

For example, fibronectin mediates contact between cell surface integrins and ECM (eg. collagen). can facilitate movement

Question 27

the membrane is...

Answer 27

is a mosaic of molecules bobbing in a fluid bilayer of phospholipids Membranes are not static...Objective Two cell specific and dynamic repertoire of membrane- bound proteins present as required

Question 28

Is the nucleus the largest distinct structure inside the cell?

Answer 28

Yes

Question 29

WHAT IS THE FUNCTION OF NUCLEUS

Answer 29

to house/protect DNA * make RNA and assemble ribosomes * pores regulate movement of substances (eg protein and mRNA) in and out * molecule segregation to allow temporal and spatial control of cell function

Question 30

Nucleus features

Answer 30

Enclosed by double lipid bilayer called nuclear envelope, continuous with rough ER Entry and exit through nuclear pores Nucleolus: rRNA production, assembly of small and large subunits of ribosomes

Question 31

DNA IN NUCLEUS FEATURES

Answer 31

DNA wrapped 2x around group of 8 histones, to form nucleosomes -collectively known as chromatin Most of the time, our DNA is present as chromatin and chromatin fibers As the cell prepares for cell division, chromatin condenses to form chromatin fibers then condenses further into loops and then stacks as chromosomes. Chromosome – comprises many genes Gene - a DNA segment that contributes to phenotype/function

Question 32

Ribosomes structure

Answer 32

two subunits, small and large made of ribosomal RNA (rRNA) in complex with many proteins like mushroom

Question 33

Function of ribosomes

Answer 33

protein production (translation), found in two places within the cell: free in the cytoplasm - making proteins to be used in cytosol (non-endomembrane destinations) OR attached to the RER - making non-cytosolic proteins/endomembrane rRNA made in nucleolus Subunits assemble in the nucleolus leave through nuclear pores Ribosomes Objective Three two subunits, small and large made of ribosomal RNA (rRNA) in complex with many proteins

Question 34

Rough Endoplasmic Reticulum strucutre

Answer 34

continuous with nuclear envelope dotted with attached ribosomes

Question 35

Rough Endoplasmic Reticulum function

Answer 35

Major function is production of: * Secreted proteins * Membrane proteins * Organelle proteins

Question 36

how do proteins enter the Rough ER

Answer 36

proteins enter lumen within the rough ER for folding Rough ER membrane surrounds the protein to form transport vesicles destined for the Golgi

Question 37

Smooth Endoplasmic Reticulum features

Answer 37

Extends from the rough ER Lacks ribosomes : doesn’t make proteins

Question 38

Smooth Endoplasmic Reticulum function

Answer 38

Major function is as a housing unit for proteins and enzymes Synthesizes lipids, including steroids and phospholipids Storage of cell-specific proteins, not all cells make all proteins Functions of Smooth ER vary greatly from cell to cell – very cell/tissue-type specific

Question 39

Golgi apparatus features

Answer 39

– receiving and modifying This complex is made up 3-20 flattened membranous sacs called cisternae, stacked on top of one another (“pita bread”)

Question 40

Golgi apparatus functions

Answer 40

Functions: modify, sort, package and transport proteins received from the rough ER using enzymes in each cisternae Formation of: * secretory vesicles (proteins for exocytosis) * membrane vesicles (PM molecules) * transport vesicles (molecules to lysosome)

Question 41

golgi to destination

Answer 41

ach sac or cisternae contains enzymes of different functions proteins move cis to trans from sac to sac Modifications occur within each sac (formation of glycoproteins, glycolipids and lipoproteins) mature at the exit cisternae travel to destination Objective Three Golgi apparatus : to destination ENDOMEMBRANE SYSTEM : Fred ( ) can be a well travelled phospholipid!

Question 42

Lysosomes features

Answer 42

contain powerful digestive enzymes vesicles formed from Golgi membrane membrane proteins pump H + in to maintain acidic pH rest of cell protected by membrane

Question 43

Lysosomes function

Answer 43

Main function is digestion of: * substances that enter a cell * cell components e.g. organelles - autophagy * entire cells - autolysis Once digested, all building blocks (amino acids, lipids, etc.) are recycled

Question 44

Mitochondria features

Answer 44

Mitochondria are made up of: * Outer mitochondrial membrane * Inner mitochondrial membrane, with folds called cristae * Fluid filled interior cavity, called the mitochondrial matrix The more energy a cell requires, the more ATP it must make, and the greater the number of mitochondria present Mitochondria carry a separate small (37 genes) genome encoding mitochondrial specific products

Question 45

Mitochondria function

Answer 45

Main function: generation of ATP through cellular respiration

Question 46

Cytoskeleton

Answer 46

Fibres or filaments that help to maintain the size, shape and integrity of the cell: *Act as scaffolding across the cell *Involved in intracellular transportation and cell movement Three types of fibers (from smallest to largest): Microfilaments Intermediate filaments Microtubules

Question 47

microfilaments FEATURES

Answer 47

Diameter: ~7 nm Comprised of actin molecules assembled in two long chains, twisted around each other Assembled and disassembled as required – they are dynamic

Question 48

microfilaments FUNCTION

Answer 48

Function: Bear tension and weight by anchoring cytoskeleton to plasma membrane proteins, and promote amoeboid motility if required (eg. macrophage) Found around the periphery and lining the interior of cell

Question 49

intermediate filaments FEATURES

Answer 49

Diameter: 8-12 nm. Comprised of diverse range of different materials; one example: keratin Found in the cytoplasm of the cell

Question 50

Intermediate filaments FUNCTION

Answer 50

Function: * bear tension and weight throughout cell, e.g., during cell anchoring, * act as scaffold for cellular organelles, e.g., the nucleus. Usually the most permanent of cytoskeletal structures – they are less dynamic

Question 51

microtubules FEATURES

Answer 51

Diameter: tubular structure, 25 nm with central lumen of 15 nm diameter Comprised of tubulin dimers (alpha and beta), coiled, to form a tube Extends from centriole into cytoplasm/nucleus

Question 52

microtubules FUNCTION

Answer 52

Functions: * Support cell shape and size * Guide for movement of organelles, * e.g., vesicles from Golgi to membrane * Chromosome organization – cell division * Support and movement of cilia /flagella