1. Cell Biology Flashcards
1
Q
What are the rules of cell theory?
A
- Living organisms are composed of cells
- Cells are the smallest units of life
- Cells come from pre-existing cells
2
Q
Explain the structure and features of a striated muscle cell.
A
- striped striated pattern
- composed of sarcomeres
- one nucleus and 30 mm long
3
Q
Explain the structure and features of a giant algae: acetabularia.
A
Structure:
- rhizoid
- stalk
- umbrella top
Features:
- 0.5 - 10 cm
- single cell
4
Q
Explain the structure and features of an aseptate fungal hyphae.
A
Structures:
- long threads with many nuclei
Function:
- no dividing cell wall called septa
- shared cytoplasm and multiple nuclei
5
Q
Describe all the functions of life in a cell.
A
- Metabolism -chemical reactions
- Growth- increase in shape and size
- Reproduction -offspring
- Response - reactions to changes in enviro
- Homeostasis - regulation of internal conditions
- Excretion - remove waste
- Nutrition - intake of nutrients
6
Q
Why can’t a virus carry out all the processes of life?
A
Do not metabolise or reproduce
Because they exhibit no properties of life outside the host cell and do not have a cellular structure
7
Q
What is the function of metabolism in paramecium and chlamydomonas?
A
- catalysed by enzymes and take place in cytoplasm
8
Q
What is the function of growth in paramecium and chlamydomonas?
A
paramecium:
- consumes = enlarges
- certain size reached = divide into two daughter cells
Chlamydomonas:
- produces organic molecules during photosynthesis and absorption of minerals causes the organisms to increase in size
- certain size reached= divide into two daughter cells
9
Q
What is the function of response in paramecium and chlamydomonas?
A
Paramecium:
- wave action of beating cilia propel in response to changes
Chlamydomonas:
- senses light changes in environment using eye spot and flagella to move towards light to increase photosynthesis
10
Q
What is the function of homeostasis in paramecium and chlamydomonas?
A
- maintained by collecting excess water in contractile vacuoles and then expelling it through plasma membrane
- helps maintain their water balance
11
Q
What is the function of nutrition in paramecium and chlamydomonas?
A
Paramecium:
- engulfs food particles in vacuoles where it digests
- soluble products are then absorbed into cytoplasm of cell
- feeds on microorganisms
Chlamydomonas:
- uses large chloroplast to carry out photosynthesis to produce own food
12
Q
What is the function of reproduction in paramecium and chlamydomonas?
A
Paramecium:
- both sexual and asexual
- divides into two daughter cells in binary fission
Chlamydomonas:
- both
- when it is a certain size, each cell reproduces
13
Q
What is the function of excretion in paramecium and chlamydomonas?
A
Paramecium:
- food vacuoles - cytoplasm - vacuole shrinks - fully digested - anal pore - expelled
Chlamydomonas:
uses whole surface of plasma membrane to excrete its waste products
14
Q
What happens to volume as cell grows?
A
volume increases much more than the surface area in a cell
15
Q
Why is dividing or folding necessary to increase the ratio of surface area to volume?
A
If a cell’s surface area is too small compared to its volume, not enough of the necessary molecules can get in and not enough waste (including heat) can get out.
16
Q
Give two examples of how folding helps with increasing the ratio of surface area to volume.
A
Folding in human brain.
- increases surface area
- allows more brain tissue to fit in small area
- helps fit our growing cortex and folding nerve signals to travel over a smaller distance
Folding in the digestive system:
- small intestine folded
- increases surface area for more absorption
17
Q
Explain the steps of evolution of multicellular organisms.
A
- grew larger
- differentiation of cells
- emergent properties
18
Q
Define emergent properties.
A
special functions and structures the whole complex system possess but not each individual part
19
Q
What is cellular differentiation?
A
a process when the specialised stem cell changes and carries out a specific function in the body
20
Q
How does stem cells help in embryo growth?
A
Early stage: fertilised egg starts to divide, some cells develop differently
The cells in the embryo are called pluripotent embryonic stem cells, meaning they can develop into any type of body cell
21
Q
Define a stem cell.
A
a stem cell is an undifferentiated cell of a multicellular organism that can form more cells of the same cell type indefinitely and from which certain other kinds of cell arise by differentiation.
22
Q
List the types of stem cells.
A
Totipotent
pluripotent
multipotent
unipotent
23
Q
What is the function of a totipotent stem cell and give examples?
A
Can differentiate into any type of cell including placental cells.
Can give rise to a complete organism.
eg. the eight cells of the morula
24
Q
What is the function of a pluripotent stem cell and give examples?
A
Can differentiate into all body cells, but cannot give rise to a whole organism.
eg. embryonic stem cells of the blastocyst
25
What is the function of a multipotent stem cell and give examples?
Can differentiate into a few closely related types of body cell.
eg. umbilical cord stem cells
26
What is the function of a unipotent stem cell and give examples?
Can only differentiate into their associated cell type. For example, liver stem cells can only make liver cells.
27
Why are embryos totipotent cells?
Once an egg has been fertilised
It starts to divide
And forms totipotent cells
Continues to divide and develop to form the pluripotent cells of the blastocyst from which all the specialised tissues of the developing embryo are generated
28
What is stargardt's disease? What is the role of stem cells in this disease?
The disease of the eye
Role:
- Retinal cells derived from human embryonic system injected into retina
- The cells become functional
- May be possible to restore eyesight to affected individuals using stem cells.
29
What is leukemia disease? What is the role of stem cells in this disease?
A type of cancer in the blood or bone marrow.
Role:
- Harvesting multipotent cells
- HSCs taken from bone marrow, peripheral blood or umbilical cord blood
- patient undergoes radiotherapy or chemotherapy to get rid of white blood cells
- HSCs injected back into bone marrow
30
Discuss the uses of stem cells in therapeutic uses.
- Cells used in therapy to treat diseases
- Transplants in human organs without killing anyone or impact on donor
- Stem cells are harvested from embryo so no pain for embryo
31
What are prokaryotes? Explain in detail.
- earliest and most primitive type of cell
- unicellular
- found everywhere
- no internal compartments
- no nucleus
- no membrane bound organelles
- all metabolic processes occur within the cytoplasm
- reproduce by binary fission
32
Explain how prokaryotes divide by binary fission.
1. chromosome is replicated semi-conservatively
2. two copies of DNA move to the opposite ends of the cell
3. Cell elongates
4. plasma membrane grows inwards and pinches off to form two identical cells
33
What is the function of cell walls in prokaryotes?
- encloses the cell
- protects and help maintain shape
- prevent cell from bursting in hypotonic media
34
What is the function of plasma membrane in prokaryotes?
- surrounds the cell
| - control movement in and out of cell
35
What is the function of cytoplasm in prokaryotes?
- fills the cell and the site of all metabolic reactions
36
What is the function of pilli in prokaryotes?
Protein filaments on the cell wall that help in cell adhesion and in transferring of DNA between two cells.
37
What is the function of flagella in prokaryotes?
- locomotion of organism
| - whip-like movement propels the cell
38
What is the function of 70s ribosome in prokaryotes?
the sites of protein synthesis
39
What is the function of nucleoid region in prokaryotes?
- controls all the activities of cell
| - reproduction of the organism
40
What is the function of plasmids in prokaryotes?
- small circles of DNA that carry few genes
| - these genes give the cell antibiotic resistance and are used in creating genetically modified bacteria
41
What are eukaryotic cells?
- has nucleus
- vary in size
- has compartments
42
Explain the compartmentalisation in eukaryotes.
- the formation of compartments within the cell by membrane-bound organelles
- eg. inside the mitochondrion is completely sealed from cytoplasm by mitochondrial envelope without being affected by other functions in the cell
43
What are advantages of compartmentalisation in eukaryotic cells?
(4)
- can change position and number of organelles in cell without affecting others
- isolation of toxic substaces away from cytoplasm
- different internal conditions for different enzymes
- greater efficiency of metabolism as the enzymes and substrates are enclosed, greater concentration
44
What is the function of cytoplasm in eukaryotic cells?
- fills cell
- holds organelles
- contains enzymes that catalyse various reactions occurring
45
What is the function of plasma membrane in eukaryotic cells?
- control movement of substances in and out of cell
46
What is the function of mitochondria in eukaryotic cells?
- site of cellular respiration in which ATP is generated
47
What is the function of 80s ribosomes in eukaryotic cells?
- sites of protein synthesis
| - produce proteins
48
What is the function of nucleus in eukaryotic cells?
- controls all activities of cell
| - reproduction of unicellular organisms
49
What is the function of nucleolus in eukaryotic cells?
- part of nucleus
| - produces ribosomes
50
What is the function of smooth endoplasmic reticulum in eukaryotic cells?
- producing and storing lipids
51
What is the function of rough endoplasmic reticulum in eukaryotic cells?
- transports protein produced by ribosomes on its surface to the golgi apparatus
- proteins for use outside cell
52
What is the function of golgi apparatus in eukaryotic cells?
- processes and packages proteins
53
What is the function of vesicles in eukaryotic cells?
- small sac that transports and releases substances produced by the cell by fusing with the cell membrane
54
What is the function of lysosomes in eukaryotic cells?
- contain hydrolytic enzymes and play important roles in the destruction of microbes engulfed by white blood cells
- destruction of old cellular organelles
55
What is the function of centrioles in eukaryotic cells?
- play an important role in the process of nuclear division by helping to establish in the microtubules
56
What is the function of vacuoles in eukaryotic cells?
- helps in the osmotic balance of the cell and in the storage of substances
- have hydrolytic functions similar to lysosomes
57
What is the function of cell wall in eukaryotic cells?
- protects the cell
- maintains its shape
- prevents it from bursting in hypotonic media
58
What is the function of chloroplasts in eukaryotic cells?
- double membrane bound organelles
- contain pigments
- responsible for photosynthesis
59
How are electron microscopes different from light microscopes?
- have much higher resolution than light
- can be used to study cellular structures, disease causing particles
light:
- live specimens
60
What is the structure of the phospholipid bilayer?
- two layers of phospholipids that are arranged according to their properties
- phosphate heads are hydrophilic because of their charge
- fatty acids are hydrophobic
61
What is the amphipathic molecule?
- a molecule that has both hydrophilic and hydrophobic parts
- hydrophilic phosphate heads face the watery environment
- hydrophobic fatty acid chains are sandwiched between the two bilayers of the phosphate heads
62
What are membrane proteins and their structures?
- a group of proteins with diverse structures
- all vary out different functions
- support the plasma membrane when it carries out its function
- can be integral or peripheral proteins depending on position
63
Differentiate between integral and peripheral proteins.
Integral proteins:
embedded in the plasma membrane
- amphipathic
- pass completely through membrane
Peripheral proteins:
- hydrophilic so attached outside the plasma membrane
64
List the functions of membrane proteins.
1. Channels: allow passive transport of substances in and out of cell
2. Carriers: proteins bind to substances on one side of membrane, these change shape to transport protein
3. Recognition: differentiate self and non-self proteins
4. Receptors: intercellular info from inside and outside
5. Enzymes: proteins that enhance the rate of reactions
65
What are the roles of cholesterol and glycolipids in other parts of cell membrane?
Glycolipids:
- phospholipids and carbohydrate attached together differientiate self and non-self cells
Cholesterol: main the structure of cell membrane and found in animal membranes
66
What is cholesterol?
- a steroid made up of a non polar part comprising four ring structure, a hydrocarbon tail and a polar hydroxyl group
- amphipathic
- membranes require cholesterol to function properly
67
What are the functions of cholesterol in animal cell membranes?
- controlling membrane fluidity and permeability to some solutes
- restricts the movement of phospholipids and other molecules
- prevents the solidification of membrane at low temperature
68
What did the Davson-Danielli membrane model suggest?
Suggests that the cell membrane comprises a lipid bilayer where two layers of polar lipid molecules are arranged with their hydrophilic head outwards
69
What were the limitations of the Davson-Danielli model?
The model gave an explanation for membranes effectiveness as a barrier to the movement of certain substances.
But:
- it was assumed all membranes had identical structures
- proteins are amphipathic
70
What did the new model of the Davson-Danielli membrane model suggest?
- suggests that proteins are individually embedded in the phospholipid bilayer
- hydrophibic portions of proteins and phospholipids were in the non-aqueous environment inside the bilayer
71
Define diffusion.
The movement of particles from a region of high concentration to a region of low concentration (down to low)
72
What factors affect various factors?
Temperature: molecules diffuse faster if higher temperature
Surface area of membrane: an increase in surface area allows more molecules to diffuse
Size of particles:
smaller = faster
larger = slower
Concentration gradient of diffusing particles: the bigger the gradient, the faster the diffusion
73
What is the process of simple diffusion?
- gas or liquid medium
- only requires concentration gradient
- molecules of gas diffused until evenly distributed
- If particle too big,it cannot go through the phospholipid bilayer
- Charged particles are also prohibited to go through
- Thus, facilitated diffusion comes in
74
What is facilitated diffusion?
- requires channel proteins or carrier proteins
| - size of the proteins determine what substance can cross through the membrane
75
How does neurons function in facilitated diffusion?
- Moves K+ ions out of the axons to cause repolarization
K+ channels would only allow K+ ions
Voltage is gated
76
What is osmosis?
The passive movement of water molecules from a region of low solute concentration to a region of higher solute concentration across a partially permeable membrane
Involves water molecules only
Just let water molecules to go through the membrane
77
How does osmosis work in tissues and organs in medical procedures?
- tissues of organs are kept in saline solution
- same concentration as the concentration of cytoplasm of the cells of tissue to prevent osmosis
- osmosis would damage cells
- tissues prevention solution prevents tissue swelling and maintaining ionic balance.
78
Define hypotonic, hypertonic, and isotonic.
Hypotonic: the concentration of solutes is greater inside the cell than outside of it so cell gains water
Hypertonic: the concentration of solutes is greater outside the cell than inside it so cell loses water
Isotonic: concentration of inside = conc of outside so no movement of water
79
Why does active transport require energy in the form of ATP?
- energy used to move substances against a concentration gradient
- from low concentration to one of a higher concentration
80
Give an example of how active transport is used in the human body.
In the epithelial cells of the small intestine, glucose is actively transported into the epithelial cells lining the small intestine. This creates a high concentration of glucose inside the epithelial cells, which then allows glucose to diffuse into the blood.
81
How are sodium-potassium pumps used for active transport?
1. When the sodium-potassium pump is open, three sodium ions enter and bind to the binding sites
2. Atp donates a phosphate group to the pump
3. This causes protein to change shape and expel Na+ to the outside
4. Two potassium enter and attach to binding site
5. This release the phosphate and causes the pump to change shape again and only open on the inside
6. K+ is released inside
7. Na+ can enter and bind again
82
What is endocytosis?
A cellular process where cells take in molecules or substances from outside and engulf them in a cell membrane
- Phagocytosis: absorption of solids
- Pinocytosis: taking in of liquids
83
What is exocytosis?
A cellular process where waste products or useful substances are ejected from inside the cell.
- Excretion: after phagocytosis, undigested remains are excreted
- Secretion:
- proteins synthesised
by ribosomes are passed to the golgi apparatus via vesicles
- packed before released in vesicles that fuse with plasma membrane for secretion outside the cell
84
What is the role of vesicles in exocytosis?
- allows movement of materials within the cells
- many of the organelles are membrane-bound so makes own vesicles
- helps move molecules around the inside cells
85
Explain the process of the secretion of enzymes out of the cell.
Enzymes:
- made in the rough ER
- rough ER package the enzymes in a vesicle formed from the membranes of the rough ER
- vesicles move to golgi apparatus and fuse with the membrane
- enzymes modified further in golgi apparatus
- packed in a vesicle created using the membrane
- vesicle will then move toward the plasma membrane and undergo exocytosis and release enzymes out of cell
86
What are the 4 conditions of the emergence of life?
1. Simple organic molecules must be formed
2. Large organic molecules must be formed by simple molecules
3. Organisms reproduce so DNA replication must be possible
4. Cell membranes are necessary
87
Explain the origin of eukaryotic cells, according to the endosymbiotic theory.
- when prokaryotes are digested by larger prokaryotes, they did not get digested and remained
- led to carrying out aerobic respiration and provide energy to host cell
- prokaryotic cells that could convert light to chemical energy became chloroplasts
88
What is the evidence that eukaryotic cells have evolved from prokaryotic cells?
1. Double membranes
2. Singular naked DNA
3. Divide by binary fission
4. Susceptible to antibiotics
