Unit 1.2 Cell structure and organisation

Question 1

Define cell theory?

Answer 1

All living things are made up of one cell or more

Question 2

What is the cell theory?

Answer 2

1. All living things are composed of cells
2. The cell is the smallest unit of life
3. Cells only arise from pre-existing cells

+ MRS GREN
Movement
Respiration
Sensitivity

Growth
Reproduction
Excretion
Nutrition

Question 3

What is the magnification formula?

Answer 3

A x M = I
I = size of image
A = size of actual
M = magnification

Re-arrange ofc but know what each symbol means

Question 4

Tell me the differences between electron and light microscopes?

Answer 4

Electron:
- Greater resolution + magnification
- Non-living only
- TEM - internal structures
- SEM - surface, 3D
- No colour

Light:
- Resolution limited due to wavelength of light
- Only one type
- U can just say the opposite of the electron microscope

Question 5

In microscopes n stuff, why would u do staining?

Answer 5

To see more details/structures more clearly
e.g. Cell division = to make chromosomes visible

Staining certain things, u need certain things

Question 6

For staining plants, what would u use?

Answer 6

Iodine

Question 7

For staining animal/DNA, what would u use?

Answer 7

Methylene blue

Question 8

So for apparently for staining, electrons = ???

Answer 8

Heavy metal ions

Question 9

Tell me all about viruses?

Answer 9

Not living as:
- They have to reproduce using another host
- Dependent on other cells
- Will die on their own

3 types and their structures:

Bacteriophage
- Looks like some spider key
- Waves line within is DNA
- I guess the walls are it’s capsid (protein sheath)

HIV (Human Immunodeficiency virus)
- Think of covid but he’s 2D squished
- Inside has enzyme as dot
- With DNA as the lines too
- Protecting it is Capsid
- Which protecting that is the envelope
- And them spikes are called envelope protein

TMV (Tabacco Mosaic Virus)
- Cylinder lego brick with a string attached
- They’re called proteins them brick walls
- And the helix string above is RNA

Virus consists of DNA or RNA, not both, enclosed in a protein coat

Question 10

Similarities & differences between a virus and an animal cell?

Answer 10

Differences:
- No cell membrane, cytoplasm or membrane-bound organelles
- Animal cells have no protein coat

Similarities:
- Contain nucleic acids

Question 11

Tell me all about the prokaryote cell

Answer 11

“Before nucleus” (Bacteria, well the one i’ll be typing here)

Structure (visuals):

• Squiggly lines mashed together is the DNA (nucleoid)
• Within the proximity:
  Cytoplasm as the background
  Ribosomes a bunch around as circles
  Mesosome - site of respiration which is like at the top and is some kinda terraria cave entrance or rather a bite
• Protecting this is the Plasma Membrane
• Which protecting that is the Cell wall
• And around all this is a Slime capsule - contains glycocalyx
• Additionally has a tail called Flagellum

Functions of each component:

DNA - reproduction
Cytoplasm - cell growth , metabolism and replication
Ribosomes - translate DNA to amino acids
Mesosome - site of respiration
Plasma membrane - provides transport of molecules
Cell wall - maintains bacterial structural integrity
Slime capsule - protection from physical and chemical attacks
Flagellum - movement (he wrote locomotion???)

Question 12

Tell me all about the plant cell

Answer 12

Quite literally just plant cell man

Structure (visuals):

• We start with the circly dark thing which is the nucleolus
• Perhaps it’s background or either squiggly lines? is the chromatin
• Three of these are inside the nuclear envelope/pore that has small gaps between the walls n stuff
• and so near the nuclear envelope:
  Rough Endoplasmic Reticulum (RER) which is actually connected to the nuclear envelope and has a bunch of ribosomes on it
  Smooth Endoplasmic Reticulum which looks similar to the RER but without any ribosomes on it and I’d say for both they look like streets from a birds view yano however for SER each street not connected
  Ribosomes which just usually a bunch around within
  Central vacuole some slime looking big thing with nothing in it
  But it’s walls are called tonoplast
  Golgi body/apparatus which actually looks like the SER but it’s more curvy and kinda rearranged like that wifi symbol
  Cytoplasm ig as for the background
  Chloroplasts which just looks like bigger circles similar to mitochondria
  And lastly mitochondria which looks like razors fr
• Protecting all this is the Plasma Membrane
• And protecting that is the Cell wall (cellulose)
• However outside of cell wall, there are prob 2 gaps called Plasmodesmata
• And actually apparently the linings of the outside of the cell wall is called lamella - thin membrane
• Sometimes there’s be Microtubules idk what for

Question 13

Differences between prokaryotes and plant cells?

Answer 13

• Plant cell wall = cellulose
  Prokaryotes = murein or peptidoglycan
• Plants membrane = bound organelles
  Prokaryotes = flagella and slime capsule

Question 14

Tell me all about eukaryotic cells

Answer 14

Animal cell

Structure (visuals):

• We start with that one circle within the big circle, the Nucleolus
• In it’s proximity is Chromatin which are the lines connected to the nucleolus
• And Nucleus which is probably the background
• Protecting all that is the Nuclear envelope/pore with the gaps between walls
• And so near the nuclear pore is the following:
  Rough Endoplasmic Reticulum (RER) that’s connected to the nuclear pore and has ribosomes on it (small circles)
  Smooth Endoplasmic Reticulum (SER) which appears to be looking like boats near the RER
  Ribosomes ofc they are in there
  Cytoplasm as the background
  Golgi body/apparatus which looks like wifi
  Golgi vesicles which are the circles near golgi body with nothing in it but looks decently the size of the others
  Mitochondria looks like a razor
  Centriole which looks like that flower and lastly
  Lysosome which looks like vesicle with stuff in it or perhaps it can be an S?
• And protecting all this is the Cell membrane
• In addition, the “bite” from the membrane is called the Secretory vesicle tho unsure if we needa know this for as level

Question 15

Similarities between eukaryotes and plant cells?

Answer 15

Both have:
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
- Chromatin
- Golgi body
- RER
- SER
- Ribosomes

Question 16

Differences between eukaryotes and plant cells?

Answer 16

Animal cells have:
- Centrioles
- Small non-permanents vacuoles such as phagocytes
- Circular shape

Plant cells have:
- Chloroplasts = creates glucose through photosynthesis
- Pigment chlorophyll
- Cell wall = cellulose
- Permanent, large vacuole = for storage
- Tonoplast = separates vacuole from cytoplasm
- Cubic shape

Question 17

Tell me all about the differences between prokaryotes and eukaryotes?

Answer 17

Size of the cell:
Prokaryotes
- Typically 0.2 - 2.0µm in diameter

Eukaryotes
-Typically 10 - 100µm in diameter

Nucleus:
Prokaryotes
- No nuclear membrane (nuclear pore) or nucleoli (nucleolus); only nucleoid (DNA)

Eukaryotes
- True nucleus, consisting of nuclear membrane and nucleoli

Membrane-enclosed organelles (organelle surrounded by phospholipid bilayer):
Prokaryotes
- Absent = folds in the cell surface membrane
- e.g. mesosomes provide increased surface area for respiratory enzymes

Eukaryotes
- Present; examples include:
- Lysosomes, golgi body, endoplasmic reticulum, mitochondria and chloroplasts

Flagella:
Prokaryotes
- Consists of two protein building blocks

Eukaryotes
- Complex; consists of multiple microtubules

Glycocalyx:
Prokaryotes
- Present as a capsule/slime lay er

Eukaryotes
- Present in some cells that lack a cell wall

Cell wall:
Prokaryotes
- Usually present, chemically complex
- Typical bacteria cell wall includes peptidoglycan

Eukaryotes
- When present, chemically simple
- e.g. cellulose

Plasma membrane
Prokaryotes
- No carbohydrates and generally lacks sterols

Eukaryotes
- Sterols and carbohydrates that serve as receptors present
- e.g. glycoproteins and glycolipids

Cytoplasm:
Prokaryotes
- No cytoskeleton
- No cytoplasmic streaming

Eukaryotes
- Cytoskeleton; cytoplasmic streaming
- E.g. phagocytosis

Ribosomes:
Prokaryotes
- Smaller size (70S)

Eukaryotes
- Larger size (80S)
- Smaller size (70S) in organelles

Chromosome (DNA) arrangement:
Prokaryotes
- Singular circular chromosome
- Lacks histones

Eukaryotes
- Multiple linear chromosomes with histones;
- Provide structural support for a chromosome

Cell division:
Prokaryotes
- Binary fission
- Asexual reproduction, duplicates DNA, then divides into two parts
- (Cytokinesis)

Eukaryotes
- Mitosis

Sexual Reproduction:
Prokaryotes
- No meiosis; transfer of DNA fragments only
- (Conjugation) = spreading genetic material through direct contact

Eukaryotes
- Involves meiosis

Question 18

Now tell me alll about each organelle

Answer 18

Nucleus
Desc:
- Double membrane-bound
- Contains the nuclear envelope and pores
- Contains chromatin, extended loosely coiled chromosomes of DNA
- And histone protein and the nucleolus

Function:
- Nuclear envelope separates contents of nucleus from rest of cell
- Pores allow transport of mRNA and nucleotides (bases)
- Chromosomes carry the genetic code for the production of proteins (to control cell activity)
- Ribosomal RNA (rRNA) is produced in the nucleolus

Diagram:
- Dark circle = nucleolus
- Squiggly lines around = chromatin
- The walls around = nuclear envelope
- The gaps between walls = nuclear pore

Nucleolus
Desc:
- Area of dense chromatin within the nucleus
- It is a granular structure and is not membrane bound

Function:
- The nucleolus makes rRNA and assembles ribosomes

Diagram:
- Like I said, dark circle within nucleus

Rough Endoplasmic Reticulum (RER)
Desc:
- Consists of flattened sacs called cisternae
- Continuous with the outer nuclear membrane and may link with golgi body/apparatus
- Studded with ribosomes

Function:
- RER is the intracellular transport system and provides a large surface area for ribosomes
- The ribosomes make protein which is then transported within the ER’s flattened sac (the sheets called cisternae)
- Some of the proteins are secreted by the cell, others are used within the cell

Diagram:
- Street view type shi
- Circles on outside = ribosomes
- Tho u can say each “street” is cisternae or flattened sac ig?

Smooth Endoplasmic Reticulum (SER)
Desc:
- Consists of flattened sacs called cisternae
- Not studded with ribosomes
- Contains enzymes that catalyse lipid reactions

Function:
- Production of lipids and steroids e.g.
- Cholesterol, phospholipids and steroid hormones

Diagram:
- Is literally like the RER but has no ribosomes

Golgi body/apparatus
Desc:
- A series of dynamic, flattened sacs

Function:
- Receives proteins packages in vesicles from the ER at one end, and releases them from the other
- Modifies proteins e.g. by adding sugars to make glycoproteins
- Packages modified proteins into vesicles for transportation to the cell surface membrane and secretion out of the cell

Diagram:
- Wi-fi looking type shi
- Tho the vesicles can contain glycoproteins or [ribosomes?]

Ribosomes 20nm (Polypeptide)
Desc:
- Not membrane bound
- Consists of 2 subunits, large and small
- Made of ribosomal RNA and protein

Function:
- The site of protein synthesis
- mRNA from the nucleus is read and used to assemble amino acids
- May be free in cytoplasm or bound to ER

Diagram:
- U find them as small circles within cytoplasm
- Or just connected to the RER

Lysosome (glycoprotein)
Desc:
- Spherical sacs from golgi body surrounded by a single layer of membrane
- Contain powerful digestive enzymes

Function:
- Protects the cell from enzymes contained within
- Enzymes are used in the breakdown of materials e.g. bacteria engulfed by WBC (white blood cell) in phagocytes
- Breakdown of old cell organelles
- Programmed cell death (apoptosis)

Diagram:
- Well is has a membrane so u know, 2 walls n stuff of the circle
- And within is enzymes/proteins

Plasma Membrane (cell surface membrane)
Desc:
- Present in all living cells
- Provides a selective barrier between the cells contents and the external environment

Function:
- Controls the passage of substances into and out of the cell
- Regulates the internal environment of the cell

Diagram:
- Well it’s the line that’s within the cell wall, if u know u know

Mitochondria (2-5µm long)
Desc:
- Consists of an outer and inner double membrane; inter-membrane space; inner-membrane folded into cristae; matrix with DNA and ribosomes

Function:
- Site of respiration
- Function is for energy production (ATP)
- Self-replicating
- Abundant in cells that are metabolically active
- e.g. liver, muscle, synopses between nerves

Diagram:
- U know, in closer inspection, it’s looks like them cartoon monster mouths
- They still have ribosomes
- The circles not connected to walls are circular DNA
- The cylinder 2D looking dark one is the phosphate granule
- The cylinder connected to wall inside is the cristae/internal matrix?
- And as it’s got 2 membranes, together called envelope

Chloroplast (4-10µm long)
Desc:
- Consists of a double outer membrane
- Containing stroma with ribosomes, lipid, circular DNA and possibly starch
- Through the stroma are parallel flattened sacs, thylakoids stacked in places as granum
- Between the granum are the thylakoids that connect granum called lamellae

Function:
- Thylakoids/granum are the site of photosynthetic pigments
- Chloroplasts, along with mitochondria are self-replication
- Abundant in palisade and mesophyll cells in the leaf

Diagram:
- Well they have an outer and inner membrane so 2 lines ig
- Thylakoids, the one stacked on top of each other
- Tho all together called a granum
- And the connections between granum is the stroma/lamellae
- Course they have ribosomes
- They have DNA too
- Sometimes has starch granule, thylakoid but bigger and not stacked
- And I think the circles on it are lipid droplets

Cellulose cell wall
Desc:
- On the outside of the plant cell’s membrane
- Made from bundles of cellulose fibers

Function:
- Supports the cell
- Helps the maintenance of the cell shape
- Fully permeable

Diagram:
- Lol the line outside of cell surface membrane

Centrioles
Desc:
- Small tubes of protein fibres (microtubules)
- There is a pair of them next to the nucleus in animal cells [and some protocists?]

Function:
- Takes part in cell division
- The spindle fibres used to move chromosomes grown from this organelle (mitosis/meiosis)
- Involved in formation of cilia and undulipodia

Diagram:
- Well its just the flowers looking organelles in the cell

Vacuole
Desc:
- Small, non-permanent vacuole in animal cells
- Large permanent vacuole in plant cells surrounded by a tonoplast

Function:
- Animal cell vacuole may be formed during phagocytosis or act as contractile vacuole
- Plant cell vacuoles function as storage site for water and solutes and maintain cell turgidity

Diagram:
- For an animal cell, pretty small with nothing in it and once again it’s non-permanent
- For a plant cell, hella big, and crazy how it has nothing in it either from our pov, in addition be aware of tonoplast, separates contents of within n shi

Cilia and undulipodia (flagellum)
Desc:
- [provisions?] from the cell
- Surrounded by the cell surface membrane
- Formed from the centroles
- Contain microtubules

Function:
- In sperm, the undulipodia (a long cilium) forms the tail for swimming
- In paramecium, more cilia are used to move the cell and to move food into the cell
- In the airways, the epithelia are ciliated to move mucus to the top of the throat

Diagram:
- It appears to be the “petals” on the centriole, if u know u know
- However ig within them petals are just more of the paired

Question 19

State the function of the lysosomes?

Answer 19

• Break down old worn out organelles and digests foreign materials
• Can cause autolysis (can destroy itself)
• And cause apoptosis (programmed cell death)

Question 20

Explain why mitochondria alter differently in a diagram?

Answer 20

Mitochondria have different cross-sections

Question 21

Tell me all the steps of protein synthesis

(apparently it’s good to know them not from beginning)

Answer 21

1. Ribosomes are produced in the nucleolus, leave the nucleus through the pores and position at the RER
2. Nuclear pores allow mRNA molecules to leave the nucleus and attach onto the ribosomes on the RER
3. Protein synthesis occurs on the ribosomes, the mRNA molecule has the code for the primary structure of a protein
4. The RER transports the polypeptides(proteins) using the transport vesicles, which merge with the golgi body
5. The polypeptides are modified in the golgi body and converted down to their tertiary structure e.g. enzymes
6. The enzyme are packaged into secretory vesicles and transported to the cell membrane. The secretory vesicles merge with the cell membrane and release the enzymes by exocytosis

Question 22

State two structures found in prokaryotic cells, are also found in mitochondria

Answer 22

• Ring of DNA (plasmid)
• Contain 70S ribosomes

Question 23

Describe 2 differences between mitochondria and prokaryotic cells such as bacteria

Answer 23

• Mitochondria does not have a flagella, whereas a prokaryotic cell does
• Mitochondria has a double membrane, whereas a prokaryotic cell does not

Question 24

Describe how the ultrastructure of a neutrophil is specialised to enable it to perform this function

(neutrophil is a phagocytic blood cell (WBC) which its function is to engulf and digest foreign cells found in the blood)

Answer 24

• Many lysosomes which contain enzymes
• Many ribosomes or RER as protein synthesis occurs and leads to enzymes
• Many mitochondria to produce ATP
• Many golgi bodies to modify ribosomes into enzymes
• Many receptor sites at cell surface membrane to detect foreign cell antigen

Lol this is inside the Neutrophil, now I get it

Question 25

Tell me about tissue

Answer 25

• Used to describe a group of similar cells found together in the body performing a particular function

The cells within a tissue share a common embryonic origin. Microscopic observation reveals that the cells in a tissue share similar morphological features and are arranged in an orderly pattern that achieves the tissue’s function optimally

Question 26

Tell me the levels of organisation

Answer 26

Atoms -> Molecules -> Organelles -> Cells -> Tissues -> Organ -> Organ system -> Organism

Tissues = an aggregation of similar cells carrying out a particular function
Organ = an aggregation of similar tissues carrying out a particular function

It’s tangible basically

Question 27

How do muscles contract?

Answer 27

• All muscles contain filaments called actin and myosin
• When a nerve impulse tells it to move, these filaments slide across each other, causing the cell to contract

Visuals:
- Myosin is the blue river lookin thing
- Which has myosin heads on the outside
- And them actin filaments are surrounding the myosin soooo ya

Question 28

Tell me about the 3 types of tissues

Answer 28

Epithelial Tissue - epithelium
1. Refers to sheets of cells that cover exterior surfaces of the body
2. Lines internal cavities and passageways
3. And forms certain glands

• This tissue type forms the lining of the body and organs (endothelium)
• Cells are closely packed together and may have cilia, they have a basement membrane connecting them
• Can be simple (one layer) or compound (several layers)
• Can have several shapes:
  Columnar (tall and thing) e.g. intestines
  Squamous (flat) e.g. blood vessels
  Cuboidal e.g. kidneys

Visuals:
Squamous: It’s quite literally flat so, ye. Perhaps a bunch of eyes shaped all together as a cube, remember it’s more flat
Cuboidal: Just like squamous but not rlly flat like that. I’d say there’s more in a row too
Ciliated columnar: So it’s tall and thin ofc. In addition, “ciliated”, so look at the top of it too

Connective Tissue
1. Binds the cell and organs of the body together
2. Functions in the protection, support, and integration of all parts of the body

• These connect different tissue types and organs together and also includes the skeleton and blood
• Cells are often far apart and from each other and connected by a fluid, solid, or semi-solid substance (the extracellular matrix)
• For example, Osteocytes, the bones are connected by a solid substance formed mostly of calcium

Visuals:
Well it’s a fluid/substance so, idk reminds me of the cohesion of H2O

Muscle Tissue
1. Excitable, responding to stimulation and contracting to provide movement
2. Occurs as three major types: Skeletal (voluntary) muscle, Smooth muscle, Cardiac muscle in the heart

• Muscle fibres are only cells which can contract and relax, this action causes the muscle tissue as a whole to contract and relax
• Muscle tissues appears striated (stripy)
• 3 main types: smooth, skeletal and cardiac
• Smooth = muscles you cannot control, found in digestive system and blood vessels
• Skeletal = muscles used to move your skeleton about a joint
• Cardiac = muscles found in your heart

Visuals:
Skeletal: Bones ig? with them dark slabs around
Smooth: A bunch of mari’s, if u know u know
Cardiac: lowkey looks like the trachea but obviously muscle stylated

Question 29

Tell me the about the locations of the cardiac and smooth muscle

Answer 29

• Smooth muscle is found in the walls of the digestive system, the respiratory system, blood vessels, the bladder and urethra and the uterus
• Cardiac muscle is found in the heart

Question 30

Tell me the similarities and the differences of the functions of cardiac and smooth muscle

Answer 30

Similarities
- Cells contract to generate movement
- They shorten when filaments inside the cell slide across each other
- Both types generate involuntary movements (you don’t think about and cannot control)
- Both controlled by an autonomous nervous system (automatic)

Differences
- Cardiac muscles contract in short but powerful bursts, whilst smooth muscles can contract for a much longer period (indefinitely if needed)
- Whilst heart is controlled by autonomous nervous system, can continue without due to peacemaker cells (cells which send electrical impulses)
- Cardiac muscle cannot regenerate if damaged; smooth muscle can regenerate

Question 31

Tell me the similarities and the differences of the structure of cardiac and smooth muscle

Answer 31

Similarities
- Cells are short, compared to skeletal muscle cells
- Cells contain actin and myosin filaments

Differences
- Th e actin and myosin in cardiac muscle are arranged into stripy sarcomeres, so tissue looks striated
- Actin and myosin is arranged “randomly” and connected at dense bodies in smooth muscle, so no striated appearance
- Cardiac muscle cells are connected at intercalated discs, which have a gap junction to allow communication between cells (cells can contract in unison) [they share several nuclei? to a fibre]
- Smooth muscle [affects smooth under microscope???] and is arranged in a bundle of fibre sheets, cells are not connected by gap junctions
- Cardiac muscle contains high number of mitochondria