Unit 1: Cells

Question 1

What are the 3 rules of Cell Theory?

Answer 1

Cell Theory:
1. All living things are composed of cells
2. Cells are the basic units of structure and function
3. Cells come from pre-existing cells

Question 2

What are the features present in all types of cells?

Answer 2

All living cells have:
- Cell Membrane
- Cytoplasm
- Ribosomes
- Genetic material
Note: Yes, this includes prokaryotic and any other cell

Question 3

What are the organelles of prokaryotic cells? (Name and Function)

Answer 3

Prokaryotic Cell Structure:
- Nucleoid Region: Where DNA is kept with no nuclear membrane
- Cytoplasm: provides optimal environment for metabolic processes
- Cell Wall: Provides structure, shape, and stability
- Cell membrane: controls substances entering/exiting the cell
- Flagella: movement or locomotion
- Pilus/Pili: helps with adhesion + transfer of plasmids
- Plasmids: Pieces of transferable circular DNA
- 70 s Ribosomes: Protein synthesis
Note: Please note that the ribosomes are 70s which is different from the 80s in eukaryotes

Question 4

What are the organelles of Eukaryotic cells? (Name and Function)

Answer 4

Eukaryotic Cell Structure:
- Cell Membrane: controls substances entering/exiting the cell
- 80s Ribosomes: Protein Synthesis
- Cytoplasm: Optimal environment for metabolic processes
- Nucleus: has double mem that allows the release of mRNA
- Mito: ATP production through aerobic respiration
- Vacuoles: for plants: storing nutrients, for Animals: waste removal
- Lysosomes: vesicles that are involved in large molecule digestion
- RER: Site of protein synthesis
- SER: Lipid synthesis and detoxification
- Golgi: Modifies/ packages proteins
- Cytoskeleton: involved in mitosis and meiosis

Question 5

DIffer between prokaryotic cell organelles and eukaryotic ones

Answer 5

Both:
- DNA
- Ribo (70s for prokaryotic and 80s for eukaryotic)
- Cyto
- Cell Mem
- Cell walls (most prokaryotic cells have cell walls)

Pro:
-No nucleus
- No MB (mem bound) organelle
- One chromosome
Loop DNA

Euk:
- Has nucleus
- Has MB organelles
- Many chromosomes
- DNA wrapped around histones

Question 6

Define Compartmentalization

Answer 6

Compartmentalization: The division/ separation of the cell’s interior

Question 7

Name all parts of a light microscope

Question 8

What is the magnification Formula?

Answer 8

Formula:
Magnification = Measured Length/ Actual Length

Question 9

Discuss the advantages and disadvantages of the light microscope vs the electron microscope

Answer 9

Light:
- easy to use and relatively cheap
- Resolution is 0.2 micrometers since it is light-dependent which can make it blurry

Electron:
- Very expensive and hard to use
- Uses electrons instead of light
- The max resolution is 0.1 nm
- Can study sub-cellular structures

Question 10

Discuss some developments in microscopy

Answer 10

Cyro- Electron Microscopes:
- Frozen specimen and electron gun shoots electrons at speed of light
- Allows for 3D images
- Clearer image

Freeze Fracture electron Microscopes:
- used to examine ultrastructures of rapidly frozen biological samples
- Liquid nitrogen used to freeze and then cracked

Immunofluorescence:
- this staining allows for us to see in their native state
- can visualize proteins or antigens by binding a specific antibody
- The sample is chemically attached to a fluorescent dye
- can study cell division and detect molecules at low conc

Question 11

What are the processes of life that all living organisms carry out? (MR HM Gren)

Answer 11

Processes of Life:
- M: Movement
- R: Reproduce
- H: Homeostasis: maintenance of internal conditions within narrow range
- M: Metabolism
- G: Growth
- R: Response to external stimuli
-E: Excretion of waste
- N: Nutrition is needed for growth

Question 12

What are some examples of atypical cell structures and explain why they are atypical?

Answer 12

Atypical cell structures:
- Red blood cells: don’t have a nucleus or anucleated
- Root Hyphae: fungal roots that are multinucleated
- Muscle cells: multinucleated which is atypical to the usual singular nucleus

Question 13

Identify differences in organelles and size between animal and plant cells

Answer 13

Organelles in Both:
- DNA
- Ribosomes
- Cyto
- Membrane
- Cell wall (most pro cells have and some euk cells have)

Pro:
- No nucleus
- No MB organelles
- One chromosome
- has Loop DNA
- smaller

Euk:
- Larger
- has nucleus + MB organelles
- Many chromosomes
- Linear DNA
- DNA wrapped with histones

Question 14

Discuss why the mitochondria were once thought to have originated from a prokaryotic cell/endosymbiosis.

Answer 14

Mitochondria:
- Has adapted to undergo aerobic cell respiration
- has a double membrane
- Has chromosomes/genetic material
- Has ribosomes
- Performs binary fission
Note: note that the list above are the features that are present in all cells thus mitochondria originated from a prokaryotic cell

Question 15

What is the endosymbiotic theory?

Answer 15

Endosymbiotic Theory: A Theory that proposes that a large cell engulfed a small aerobic prokaryotic cell where it developed a symbiotic relationship.

An example is the mitochondria and the cell where the mito offered ATP production and the cell offered protection. Or the chloroplast

Question 16

What is the evidence for the endosymbiotic Theory?

Answer 16

Chloroplast and the Mitochondria:
They share many characteristics with modern-day prokaryotic cells:
- They have 70s ribosomes
- They have a singular chromosome with naked DNA
- They reproduce via binary fission
- They have double membranes (the inner mem is the prokaryotic while the outer is from the bigger cell via endocytosis)

Question 17

Outline the advantages of multicellularity

Answer 17

Advantages:
- More efficient organisms which lead to longer lifespans
- More efficient use of resources
- Larger than unicellular organisms so can consume other organisms for energy

Question 18

What compartments of the cell aren’t considered organelles + Why?

Answer 18

Compartments not considered an organelle:
- Cell wall: because it’s an extracellular structure
- Cytoplasm: it’s not compartmentalized
- Cytoskeleton: also not compartmentalized

Question 19

What is cell fractionation?

Answer 19

Cell Fractionation: a process in which we isolate cell organelles as a way to study it.

Steps:
1. The sample is homogenized which means it’s blended up/broken up. The sample has to meet 3 criteria: cold, PH buffered, and isotonic which are all to prevent organelle damage.
2. the solution is filtered to remove large debris.
3. It is put inside a microcentrifuge where it spins slowly and then increases in speed. This machine isolates different organelles based on molecular weight. (lighter organelles form PELLETS at the top while heavier ones form at the bottom)

Question 20

Discuss why the nucleus and the cytoplasms were separated in compartmentalization

Answer 20

Separation:
- DNA is found in the nucleus and is protected by the nucleus from potentially harmful processes in the cytoplasm
- the transcription of DNA to mRNA occurs in the nucleus. The nucleus separates the metabolism that occurs in cyto to the transcription that occurs in the nucleus.
- The mRNA leaves the nucleus to be translated into polypeptides in ribosomes

Question 21

Discuss how transcription and translation occur in prokaryotic cells (no nucleus).

Answer 21

Prokaryotic Transcription/Translation:
- as mRNA is being transcribed, ribosomes attach to the mRNA and translation can begin
Note: Should be rewritten If they’re is more info on protein synthesis later on

Question 22

Discuss the advantages of compartmentalization in cells.

Answer 22

Advantages
- Greater efficiency
- provide a protective environment, for specialized processes inside the cell
- Organelles can store metabolites or enzymes which aren’t compatible with the metabolism outside of the organelle in cyto.

Question 24

What is endocytosis, exocytosis, and phagocytosis?

Answer 24

Endocytosis: a cellular process where substances from outside the cell are taken in via secretory vesicles

Exocytosis: the fusion of secretory vesicles to release it’s contents outside the cell.

Phagocytosis: endocytosis in a phagocytes (a type of white blood cell)

Question 25

Explain the process of phagocytosis

Answer 25

Phagocytosis:
- pathogens are taken in from an invagination of the cell as a phagocytic vacuole
- lysosomes in the cell fuse w/. this vacuole releases its enzymes to digest the pathogens
- then exocytosis occurs
Note: The phagocytes (type of white blood cell) can also be called Macrophages

Question 26

Outline the compartments of the mitochondria.

Answer 26

Mitochondria components:
- Outer mem: regulates things going in and out, allows molecules in for cell respiration, allows pyruvate to enter
- Ribosomes: protein synthesis, are called mitoribosomes, 70 s, in the matrix
- Cristae: many folds increasing surface area = maximizing ATP production
- Inner mem: ATP synthesis, highly folded for more proteins
- Matrix: cytoplasm of mito, has DNA and ribosomes, location of enzymes for kreb’s cycle
Note: Rewrite if there is more information

Question 27

What is the purpose of the chloroplast in plants?

Answer 27

Chloroplast:
- the pigment chlorophyll is found in the chloroplast which absorbs light energy and is used to perform photosynthesis

Question 28

Outline the chloroplast’s components

Answer 28

Chloroplast:
- Thylakoid mem: is along the mem, chrolophyll is here, make ATP by using sunlight through ATP synthase, is folded for more light absorption
- Granum: stack of thylakoid mem, flatted to increase surface area, small space inside to allow for proton accumulation
- Stroma: cyto of chloroplast, has DNA, site of light- independent reaction (Calvin Cycle)
- Thylakoid space: space between thylakoid for proton accumulation
- Ribosomes: for protein synthesis

Question 29

Outline the benefits of the double mem in the nucleus

Answer 29

Nucleus:
- mRNA leaves the nucleus via the pores because it’s too big to go through the nucleuar mem which goes to ribosomes to make proteins
- allows for many vesicles to be made during mitosis from the double mem

Question 30

Discuss the composition of the ribosome

Answer 30

Ribosome:
- they’re made of a large ribosomal unit and a small ribosomal unit which are made out of proteins and rRNA((ribosomal RNA)

Question 31

What are bound ribosomes and free ribosomes

Answer 31

Bound:
- Ribosomes that are bound to the RER
- Produces enzymes to be exported
- translation occurs here and is sent out of the cell
- to synthesize polypeptides

Free:
- in the cytoplasm
- makes proteins that stay within the cell
- translation can occur here
- to synthesize polypeptides

Question 32

Outline the composition and purpose of the golgi apparatus

Answer 32

Golgi:
- is composed of a series of flattened sacs called cisternae
- vesicles containing proteins move to the golgi form the RER to fuse with the Golgi
- Golgi modifies the proteins into vesicles to be sent out of the cell via exocytosis

Question 32

What is the protein that helps in vesicle formation and what substances need to be excreted out of the cell?

Answer 32

Protein:
- The protein is a three-legged protein that supports the fusion of membranes during vesicle formation known as budding

Substances:
- substances such as hormones, enzymes or membrane proteins need to be transported out of the cell

Question 33

Outline the composition of the cell mem and its properties

Answer 33

Comp:
- is made of a phospholipid bilayer with a hydrophilic/polar phosphate head and a hydrophobic/ non-polar fatty acid tail so its amphipathic

Properties:
- It is semi-permeable so it allows some molecules while others can’t
- the bilayer moves around giving it flexibility and fluidity

Question 34

Discuss the composition/properties of a phospholipid

Answer 34

Comp:
- theres 2 fatty acid chains and a phosphate head bonded to a glycerol molecule
- fatty acids are amphipathic
- phospholipids naturally form bilayers when added to water

Question 35

What type of molecules can enter the cell mem without facilitated diffusion?

Answer 35

Type:
- the cell mem has high permeability to small and uncharged molecules
- The cell mem has low permeability to large and charged molecules

Question 36

What is kinetic theory?

Answer 36

Kinetic theory:
- everything is in constant motion in random directions

Question 37

What is simple diffusion, facilitated diffusion, and active transport?

Answer 37

Simple diffusion:
- A form of passive transport that moves along the conc gradient and doesn’t need energy

Facilitated Diffusion:
- Assisted diffusion for molecules that can’t diffuse simply across cell mem
- doesn’t need energy
- charged ions require a protein channel to pass through called transport proteins

Active Transport:
- transport needing energy and going against the conc gradient and needs energy
- to get energy: when the last phosphate is broken, it release a lot of ATP needed for active transport EX: sodium/potassium pumps

Question 38

Define osmosis

Answer 38

Osmosis:
- passive transport of water from a low to a high conc
- in body: through aquaporins

Question 39

What are intergral and peripheral mem proteins and function?

Answer 39

Intergral:
- Proteins that are embeedded iwhtin the cell mem
- Attached to the cell mem and penetrate through the cell mem
- can be transmembrane or only partially penetrate bilayer
- Can be glycoproteins, channels or pumps
- has a hydrophobic and hydrophilic region, if its in fatty acid = hydrophobic, and vice versa

Peripheral proteins:
- hydrophilic on the surface
- attach to integral proteins or hydrophilic phosphate head of bilayer
- does not penetrate bilayer but is on the surface of cell mem
- can act as enzymes or receptors

Functions of both:
- cell adhesion, enzymatic, pumps for active transport, cell to cell communication, cell attachment, hormone binding

Question 40

What are pumps for active transport in the body?

Answer 40

Pumps:
- these pumps are for molecules that are hydrophilic or charged
- delivered across the conc gradient and uses ATP

Steps to active transport across cell mem:
1. a specific particle binds to a binding site on a protein pump
2. ATP binds to a protein pump an hydrolyzes to become ADP
3. a phosphate remains attached to the protein pump and the pump changes shape
4. The particle is moved against the conc gradient and released
5. phosphate is released and the pump changes back to the original shape

Question 41

What are some factors that affect simple diffusion?

Answer 41

Factors:
- Conc gradient: the greater the diff, the greater the amount diffused in a given time
- Distance of diffusion: shorter = quicker
- surface area: larger surface = longer
- size and type of molecule: smaller uncharged = slower diffusion
- Temp: higher temp = faster diffusion

Question 42

What are saturated and unsaturated fatty acids and how they respond to temp change?

Answer 42

Saturated:
- single bonds between the carbons in the hydrocatbon chain
- are linear and have a higher MP

Unsaturated:
- at least one double bond between carbons on the hydrocarbon chain
- bend at position of double bond called kinks
-lower MP

Temp:
- Overtime, as temp lowers, the conc of unsaturated fatty acids increases

Question 43

What are glycoproteins and glycolipids?

Answer 43

Glycoproteins:
- mem protein w a carbohydrate chain attached

Glycolipid:
- phospholipid with a carbohydrate chain attached

Question 44

What were the conditions of early Earth + what caused the spontaneous generation of organic compounds

Answer 44

Conditions:
- oxygen: conc was low because it reacted w other compounds
- methane: conc was high cause volcanic activity
- co2: conc was high causing volcanic emissions
-temp: was high causing greenhouse gas effect
ozone: barely existed cause lack of o2 due to UV radiation

Generation:
UV radiation + temperature during early earth = the spontaneous generation of organic compounds and was replicated in Miller Urey experiment

Question 45

What type of molecules are unable to pass through the plasma membrane?

Answer 45

Type:
- Since the cell mem has low permeability, large and charged molecules can’t enter
- Vice versa is true as well