Cell Biology Flashcards
1
Q
Mitosis
A
when a cell splits into two identical copies of the original cell
2
Q
Meiosis
A
when cells split into two new cells with half the usual number of chromosomes in order to form gametes for sexual reproduction
3
Q
Embryonic plant
A
this is a pluripotent cell which comes from an inner mass of a blastocyst, an early stage pre-implantation embryo.
4
Q
Pluripotent definition
A
refers to a stem cell that has the potential to differentiate into any 3 germ layers: endoderm, mesoderm or ectoderm
5
Q
How does the multinucleate cytoplasm of a fungal hyphae and skeletal muscle bring the cell theory into question?
A
The cell theory states that cells are the smallest unit of life. The skeletal muscles are long(strips) cytoplasm and fungal hyphae are multinuclear. These do not match the cell theory and are not sufficient in proving the cell theory as they are not strictly made of cells
6
Q
How does Acetabularium, the giant algal cell that can grow up to 10cm in length and has distinct body parts, disturb the cell theory?
A
It is a whole organism and is longer than a cell. It is also not made of cells so it goes against the theory that all organisms are made up of cells. Also it has 3 parts rather than 1 unit which doesn’t go with the cell theory
7
Q
hyphae
A
main mode of vegetative growth
8
Q
what are stem cells
A
they develop into many different types of cells in the body during the early stages of life and growth. They also act as an internal repair system, dividing essentially without limit to replenish other cells. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
9
Q
How do stem cells treat diseases?
A
Stem cell transplant
10
Q
What are prokaryotes
A
A microscopic single-celled organism which has neither a distinct nucleus with a membrane nor other specialized organelles, including the bacteria and cyanobacteria
11
Q
Ribosomes
A
these are a minute particle consisting of RNA and associated proteins, found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins
12
Q
what is RNA?
A
acts as a messenger carrying instructions from DNA for controlling the synthesis of proteins
13
Q
Features of prokaryotes
A
- Don’t have a membrane bound nucleus & membranous organelles
- contain DNA and ribosomes within the cell
- Have plasma membranes to protect them from their surrounding environment
- Its cellular components are found within cytoplasm
- Contains 70s ribosome
- All bacteria are prokaryotes
14
Q
Function of the plasma membrane in Prokaryotes (P)
A
responsible for controlling what gets in and out of the cell. Proteins located here also help the prokaryote cell communicate with the surrounding environment
15
Q
Function of cytoplasm in (P)
A
Contains a complex and functional cytoskeleton which helps the cell to divide and helps maintain its round, plump shape
16
Q
Function of cell wall in (P)
A
maintains shape and protects cell from bursting if internal pressure is high
17
Q
function of plasmid in (P)
A
additional DNA that can exist and replicate independently
18
Q
function of the Flagellum/Flagella in (P)
A
Contains a motor protein which spins the flagella like a propeller enabling movement
19
Q
function of the Pili in (P)
A
(attachment) shorter in length, they allow bacteria to adhere to one another of the available surfaces
20
Q
function of the Sex Pili in (P)
A
allows for exchange of genetic material(plasmids) by a process called bacterial conjugation
21
Q
What are polysaccharides
A
a molecule whose molecules consist of a number of sugar molecules bonded together
22
Q
what is binary fission
A
the division of cell in the proctor cells
23
Q
Steps of binary fission
A
- cell replicates its DNA
- Cytoplasmic membran elongates, separating DNA molecules
- Cross wall forms; membrane invaginates
- Cross wall forms completely
- Daughter cells
24
Q
draw the procaryote cell
A
label also!
25
Draw the eukaryote cell
label also
26
function of the Cell Membrane in the (E)
semi-permiable barrier that controls the entry and exit of substances
27
function of the cytosol in the (E)
The fluid portion of the cytoplasm
28
function of the nucleus in the (E)
site of the production and assembly of ribosome components
29
ribosome size in (E)
80s
30
function of the mitochondria in the (E)
Site of aerobic respiration, which produces large quantities of chemical energy(ATP) from organic compounds
31
function of the Golgi Apparatus in the (E)
An assembly of vesicles and folded membranes involved in the sorting, storing and modification of secretory products
32
function of the lysosome in the (E)
site of hydrolysis/digestion/breakdown of macromolecules
33
function of the peroxisome in the (E)
catalyses breakdown of toxic substances like hydrogen peroxide and other metabolites
34
function of the centrioles in the (E)
microtubule-organising centres involved in cell division (mitosis/meiosis and cytokinesis)
35
function of the endoplasmic reticulum in the (E)
a system of membranes involved in the transport of material between organelles
36
function of the rough ER in the (E)
studded with ribosomes and involved in the synthesis and transport of proteins destined for secretion
37
function of the smooth ER in the (E)
involved in the synthesis and transport of lipids and steroids, as well as metabolism or carbohydrates
38
what are the similarities between Eukaryotes and Prokaryotes
Both have a cell membrane
Both contain ribosomes
Both have DNA and cytoplasm
39
Magnification formula
image/actual
40
function of the secretory vesicle in Exocrine cell from Pancreas?
release chemicals and proteins from inside the cells to outside the cell wall
41
Function of the Exocrine cell from Pancreas?
Secrets pancreatic fluid that contains digestive enzymes that pass to the small intestines
42
Function of the Palisade mesophyll cell?
Site of photosynthesis
43
the structure of biological membrane does what?
makes cells fluid and dynamic
44
List some examples of membranes
plasma membran, nuclear membrane, vacuole-membranebound , endoplasmic reticulum-folded membrane, lysosome-membranebound & Golgi apparatus-folded membrane
45
How do phospholipids form?
They form bilayers in water due to the amphipathic properties of phospholipid molecules
46
what are phospholipids?
they are an inorganic phosphate group with lipid molecules made up of: glycerol & fatty acid tails
47
what are Amphipathic molecules?
molecules that have both hydrophilic & hydrophobic properties
48
Hydrophilic means?
This means 'it' attracts water molecules
49
hydrophobic means?
it does not attract water molecules
50
draw the structure of a cell membrane from notes and label
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51
Draw the phospholipid structure and label
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52
what are the structural properties of the Phospholipid Bilayer?
- phospholipids are held together in a bilayer by hydrophobic interaction(weak associations)
- hydrophilic/hydrophobic layers restrict entry and exist of substances
- phospholipids allow for membrane fluidity/flexibility
- phospholipids can move horizontally or occasionally laterally to increase fluidity
- fluidity allows for the braking/remaking of membranes
53
what are the functions of Membrane Proteins?
TRACIE
Transport-Protein channels (facilitated) and protein pumps(active)
Receptors-Peptide-based hormones(insulin)
Anchorage-cytoskeleton attachments and extracellular matrix
Cell recognition-MHC protein and antigens
Intercellular joining- tight junctions
Enzyme activity- metabolic pathways (e.t.c)
54
what is diffusion?
the net movement of particle from a region of high concentration to a region of low concentration, down a concentration gradient until equilibrium
55
what is osmosis?
the net movement of water molecules across a semi-permeable membrane from a region of low water potential to a region of high water potential, down a water potential gradient until equilibrium is reached
56
what is simple diffusion?
small, non-polar (lipophilic) molecules can freely diffuse across the membrane
57
what is facilitated diffusion?
larger, polar substances (ions, macromolecules) cannot freely diffuse and require the assistance of transport proteins(carrier proteins and channel proteins) to facilitate their movement (facilitated diffusion)
58
what is the role of ATP in active transport?
The process of Active transport requires the use of protein pump and these protein pumps use ATP to move the molecules against the gradient.
59
How does ATP help protein pumps?
The hydrolysis of ATP causes a conformational change in the protein pump resulting in the movement of the substance
60
why protein pumps in active transport?
Protein pumps are specific for a given molecule, allowing for movement to be regulated (e.g.. to maintain chemical or electrical gradients)
61
what is Active Transport?
the passage of materials against a concentration gradient from low to high)
62
how are vesicles used to transport materials within a cell between the endoplasmic reticulum, Golgi apparatus and plasma membrane? (steps)
1. Polypeptides destined for secretion contain an initial target sequence (a signal recognition peptide) which directs the ribosome to the endoplasmic reticulum
2. The polypeptide continues to be synthesized by the ribosome into the lumen of the ER, where the signal sequence is removed from the nascent chain
3. The polypeptide within the rough ER is transferred to the Golgi apparatus via a vesicle, which forms from the budding of the membrane
4. The polypeptide moves via vesicles from the cis face of the Golgi to the trans face and may be modified along the way
5. The polypeptide is finally transferred via a vesicle to the plasma membrane, whereby it is either immediately released(constitutive secretion) or stored for a delayed release in response to some cellular signal
63
draw a simple diagram and label based on notes
if you get it right you can rate this 5 :)
64
what is Endocytosis?
The process by which large substances (or bulk amounts of smaller substances) enter the cell without traveling across the plasma membrane
65
what are the two main types of endocytosis?
1. Phagocytosis
| 2. Pinocytosis
66
what is phagocytosis?
The process by which sold substances( e.g. food particles) are ingested(usually to be transported to the lysosome for break down)
67
what is Pinocytosis?
The process by which liquids/solutions (e.g. dissolved substances) are ingested by the cell (allows quick entry for large amounts of substance)
68
what is exocytosis?
The process by which large substances exit the cell without traveling across the plasma membrane. Vesicles(usually from the Golgi) fuse with the plasma membrane expelling their contents into the extracellular environment
69
Draw a simple diagram of Exocytosis using your notes and label
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70
what does Amitotic mean?
Relating to or denoting the division of a cell nucleus into two parts by constriction without the involvement of a mitotic apparatus
71
define Quiescent?
state of dormancy
72
what is the interphase?
This is the phase in the cell cycle where stages G1, S and G2 take place and is the longest part of the cell cycle as it prepares for division.
73
what happens in the G1 stage of the cell cycle?
Stage where the cell goes, duplicates organelles, synthesizes proteins and produces ATP
74
what happens in the S stage of the cell cycle?
The stage during which DNA is replicated
75
what happens in the G2 stage of the cell cycle?
Copied DNA is checked here for fidelity(mutation) and final metabolic reactions occur
76
what is the M phase in the cell cycle?
The period of nuclear division(mitosis) and cytoplasmic division
77
what is cytokinesis?
This is the cytoplasmic division of a cell at the end of mitosis or meiosis, bringing about the separation into two daughter cells
78
what happens when cell division occurs?
The cell cycle is controlled by complex chemical control system that responds to signals both inside and outside of the cell. Tumor suppressor genes produce proteins which inhibit cell division, while proto-oncogenes produce proteins that promote growth and division. Mutations to these genes result in uncontrolled cell division, resulting in the formation of a tumor.
79
what are the four phases of mitosis?
Prophase, Metaphase, Anaphase,Telophase
80
what happens in the Prophase of mitosis?
DNA supercoils, causing chromosomes to condense and become visible under a light microscope. As DNA was replicated during interphase, the chromosomes are each comprised of two genetically identical sister chromatids joined at a centromere. The centrosome move to opposite poles of the cell and spindle fires begin to form between them. The nuclear membrane is broken down and disappears.
81
what happens in the metaphase of mitosis?
Spindle fibres from the two centrosomes attach to the centrosome of each chromosome
Contraction of the microtubule spindle fires cause the chromosomes to line us separately along the center of the cell.
82
what happens in the Anaphase of mitosis?
Continued contraction of the spindle fibres cause the two sister chromatids to separate and move to the opposite poles of the cell
Once the two chromatids in a single chromosome separate, each constitutes a chromosome in its own right
83
What happens in the Telophase of mitosis?
Once the two sets of identical chromosomes arrive at the poles, the spindle fibers dissolve and new nuclear membrane reforms around each set of chromosomes. The chromosomes decidedness and are no longer visible under a light microscope. The division of the cell into two daughter cells(cytokinesis) occurs currently with telophase
84
Explain how mitosis produces two genetically identical nuclei
Durin interphase the DNA was replicated to produce two copies of genetic material. These 2 identical DNA molecules are identified as sister chromatids and are held together by a single centromere. During the events of mitosis , the sister chromatids are separated and drawn to opposite poles of the cell. When the cell divides(cytokinesis), the two resulting nuclei will each contain one of each chromatid pair and thus be genetically identical
85
What is the importance of mitosis in Growth?
Multicellular organisms increase their size by increasing their number of cells through mitosis
86
What is the importance of mitosis in Asexual Reproduction?
Certain eukaryotic organisms may reproduce asexually by mitosis. (e.g vegetative reproduction)
87
What is the importance of mitosis in Tissue Repair?
Damaged tissue can recover by replacing dead or damaged cells
88
What is the importance of mitosis in Embryonic Development?
A fertilized egg (zygote) will undergo mitosis and differentiate in order to develop into an embryo
89
How do cyclins work? (They control the cell cycle)
Cyclins bind to enzymes called cyclin dependent kinases (CDK) which become active and attach phosphates (phosphorylation), to other proteins in the cell. Phosphorylation activates other proteins in the cell to carry out tasks specific to one of the phases of the cell cycle.
90
Explain cytokinesis in plants
vesicles move to the equator of the cell where they fuse to form tubular cell plates. The cell plates merge to form two layers of membranes which develop into the plasma membrane of two daughter cells. Later a middle lamella that will link the new cell walls is formed by pectin and other substances brought in vesicles and deposited by exocytosis between the 2 new membranes. Cellulose is also brought in to further build the cell wall
91
Draw a diagram to show Cytokinesis in plant cells
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92
Explain cytokinesis in animals
A ring of contractile protein (actin and myosin) causing the plasma membrane to be pulled inwards around the equator of the cell to form a cleavage furrow. When the furrow reaches the center, the cell is pinched apart in 2 daughter cells.
93
What is the role of mitosis in living organisms?
GATE
Growth
-multicellular organisms increase their size by increasing their number of cells by mitosis
Asexual reproduction
-certain eukaryotic organisms may reproduce asexually by mitosis
Tissue Repair
-damaged tissue can recover by replacing dead or damaged cells
Embryonic Development
-a fertilized egg (zygote) will undergo mitosis and differentiate in order to develop into an embryo
94
what is Mitosis Index
This id the ratio of cells in a tissue that are undergoing mitosis. It can be used for predicting the presence of cancer cells to chemotherapy. (normal dividing cells usually have low mitotic index, while malignant concurs cells have high mitotic indexes)
95
How do we calculate Mitotic Index
of cells in mitosis/ total 3 of cells
As a percentage: (# of cells in mitosis/ total # of cells) x 100
96
How does a primary cancer tumor become a secondary tumor?
* A primary tumor is malignant tumor growing at the site where the abnormal growth first occurred.
* Cancerous cells can detach from the primary tumor
* Some cancerous cells gain the ability to penetrate the walls of lymph or blood vessels and hence circulate around the body.
* The circulating cancerous cells invade tissues at a different location and develop by uncontrolled cell division into a secondary tumor
97
What is metastasis?
the movement of cells from a primary tumor to set up secondary tumors in other parts of the body.
98
what are tumors?
These are abnormal growth of tissue that develop at any stage of life in any part of the body.
99
What is a mutation?
a change in an organisms genetic code.
100
What is a mutagen?
agents that cause gene mutations. Not all mutations result in cancers, but anything that causes a mutation has the potential to cause cancer.
101
List 4 forms of mutagens
• chemicals that cause mutations are referred to as carcinogens
• high energy radiation such as X-rays
• shortwave ultra violet rays/light
some viruses e.g hepatitis B virus causes liver cancer.
102
what are some other factors that increase the probability of tumor development(other than exposure to mutagens)
1. Great number of cells(the greater the number of cells, the greater the chance of mutation)
2. longer life span
103
What are the four main types of stem cells?
Totipotent, Pluripotent, Multipotent and Unipotent.
104
What do Totipotent stem cells do?
Can differentiate into any type of cell
105
What do Pluripotent stem cells do?
Can differentiate into many types of cell
106
What do Multipotent stem cells do?
Can differentiate into a few closely-related types of cell
107
What do Unipotent stem cells do?
Can regenerate but can only differentiate into their associated cell type (e.g.. liver stem cells can only make liver cells)
108
How do stem cells treat Stargardt's disease. Fully explain the problem and the treatment.
The problem:
- Affects around one in 10,000 children
- Recessive genetic condition(condition)
- The mutation cause an active transport protein on photoreceptor cells to malfunction
- The photoreceptor cells degenerate
- The production of a dysfunctional protein that cannot perform energy transport
- that causes progressive, and eventually total, loss of central vision
The treatment:
- embryonic stem cells are treated to divide and differentiate to become retinal cells
- the retinal cells are injected into the retina
- the retinal cells attach to the retina and become functional
- central vision improves as a result of more functional retinal cells
109
How do stem cells treat Leukemia? Fully explain the treatment and the problem
The problem:Cancer of the blood or bone marrow, results in abnormally high levels of poorly-functioning white blood cells.
The treatment:
- Hematopoietic Stem Cells(HSCs) are harvested from bone marrow, peripheral blood or umbilical cord blood
- Chemotherapy and radiotherapy used to destroy the diseased white blood cells
- New white blood cells need to be replaced with healthy cells
- HSCs are transplanted back into the bone marrow
- HSCs differentiate to form new healthy white blood cells
