Cellular Biology Flashcards
1
Q
What is the difference with resolution and
magnification?
A
Magnification is the ability to make an object seem larger than it actually is while resolution is the ability to distinguish detail.
2
Q
What is numerical aperature?
A
This shows the level of resolution the higher it is the greater the resolution
3
Q
what are the different power levels of the microscope?
A
x4, x10, x40, x100 oil
4
Q
delete
A
delete
5
Q
What is a cell?
A
this is a basic unit of organisation or structure of all living matter
6
Q
what do all true cells share?
A
Genes (DNA, RNA), Plamsa membrane, Metabolic Machinery
7
Q
What are the structures that all true cells share?
A
Ribosomes, Plasma membrane, ctyoplasm
8
Q
What are the beliefs of the Cell theory?
A
- All living organisms are made up of one of more cells and cell products
- All metabolic reactions in unicellular and multicellular organisms take place in cells
- Cell originate from other cells
- The cell is the smallest clearly defined unit of life.
9
Q
What are the domains that all living organism are classified into?
A
Archaea, Bacteria, Eukarya
10
Q
How do prokaryotes reproduce?
A
Binary Fission
11
Q
explain the process of binary fission?
A
The cell replicates its DNA. Then the cytoplasmic membrane elongates separating DNA molecules. Then the cross wall forms separating the daughter cells.
12
Q
what are the different ways genetic variation can take place in prokaryotic cells?
A
Transformation. Transductions. Conjugation. Transposable element.
13
Q
How does transformation take place?
A
This is when a bacterial cell with is own chromosomal DNA can pick up a plasmid from the surrounding environment
14
Q
How does Transduction take place?
A
Viruses release its DNA into a host cell and the host cell makes copies of the viral DNA viral protein will then be made. The bacterial DNA and the viral DNA can combine with the viral protein. therefore the next time a viral does and releases its DNA into another cell the bacterial da will get spliced into the host chromosomes.
15
Q
How does conjugation take place?
A
Bacteria that contains f+ plasmids (donor cell) will connect its pills with a f- (recipient cell). the donor cell will introduce its f+ plasmid to the new cell making it into new donor cell.
16
Q
How does transposable element form of genetic variation take place?
A
fractions/pieces of DNA molecule that can be transposed, removed and moved into another DNA molecule
17
Q
What colour are gram positive cells?
A
purple
18
Q
What colour are gram negative cells?
A
pink
19
Q
what are the different eukaryotic kingdoms?
A
Kingdom Fungi
Kingdom Plantae
Kingdom Animalia
Kingdom Protista
20
Q
What does law of instant volume mean?
A
Cell volume remains constant for a particular cell type. and is independent of the size of the organism…liver cells in the liver of a cow and the liver of a humans is the same size
21
Q
What is the endosymbiotic cell theory?
A
Infolding of plasma membrane allowed for development of internal structures.
aerobic bacteria engulfed.
endosymbiotic relationship would’ve formed with the bacterium host using oxygen, various process and producing atp and the cell protecting the bacteria.
became co-dependent bacteria lost its functions and transferred genes to the host cell.
Host engulfed photosynthetic bacterium and can now carry out photosynthesis.
22
Q
what is the result of the endosymbiotic process?
A
the development of Mitochondria and chloroplast
23
Q
Name single membrane organelles
A
Golgi, lysosomes, peroxisomes, vacuoles, vesicles
24
Q
Name double membrane organelles
A
Nucleus, Mitochondria, Chloroplast
25
Why do organelles need membranes?
Structure- plasma membrane is amphipathic - has both hydrophilic and hydrophobic parts which allows it to be selectively permeable.
Function- allows endocytosis and exocytosis to take place. also allows compartmentalization
26
What are the advantages of organelles?
1. Division of labour between compartments
2. Molecules kept away from each other to prevent inappropriate reactions and allow reactions to coexist at the same time
3. Reactions can proceed efficiently
4. Membrane can regulate uptake and explosion of materials
5. Different parts of a multistep process can occur at the same time.
27
delete
delete
28
Name structures that aren't true organelles?
Ribosomes, Cytoskeleton, Extracellular Matrix
29
Differences with (Prokaryotes) Bacteria Archaea and Eukaryotes?
Cell structure Bacteria. Archaea. Eukaryotes
Size. 0.5-1. 0.5-1. 5-20
nucleus. no no yes
Chromosome. 1 1 1>
shape circular circular linear
haploid. haploid diploid
histones no yes yes
cell division binary. binary mitosis/meosis
30
what are the functions of the plasma membrane?
1. Maintains integrity
2. regulates movement of metabolic reactions to other cells
3. regulates influx and efflux of materials
4. compartmentalisation
5. Osmoregulation
6. Antigen to antibody recognition
7. Tissue formation (cell adhesion)
8. cell to cell recognition
9. allows cell/ organelle motility
31
What are the compositions of the plasma membrane?
Lipids, Proteins, Cholesterol, Carbohydrates
32
What are integral proteins?
They are responsible for channeling ions, signalling and attachment points.
33
What are peripheral proteins?
These are usually attachment points for integral proteins
34
Whats the importance of the lipid component of the plasma membrane?
This helps to maintain fluidity and integrity of the plasma membrane. Also it is the first barrier against hydrophilic substances.
35
what happens to the bilayer at low temperatures?
The bilayer becomes tightly packed. (gel phase)
36
What happens to the bilayer at high temperatures?
The bilayer melts (fluid phase) movements allowed
37
What is the importance of cholesterol to the plasma membrane?
1. Makes the bilayer less deformable
2. Decreases it permeability to small water soluble molecules
3. Prevents crystallisation of hydrocarbons and phase shifts in the membrane
4. without cholesterol an animal cell would need a cell wall
38
What is the importance of carbohydrates in the plasma membrane?
This can be attached to lipids (glycolipids) or proteins (glycoproteins). they can also be protective, insulants and sites of receptor binding.
39
Whats the importance of proteins in the plasma membrane?
1. movement of materials
2. Diffusion. Active transport, osmosis, facilitated diffusion
3. Receptors (glycoproteins)
4. Enzymes systems
5. Ionospheres (chemicals that irreversible binds ions
40
What is the functions of the cytoplasm?
Energy transfers. Cell expansion. Growth.
Replication of organelles. Gives cell its shape.
Home of the cytoskeleton.
Storage place for chemical substances.
41
What does the cytoplasm comprise of?
Cytoplasmic matrix/ cytosol.
colloidal suspensions.
inclusions: Crystalline or soluble.
Constitute the microtrabecular lattice
42
what is colloidal suspension?
This is when particles dont settle but stay suspended (cytoplasm)
43
What is the cytoplasmic matrix/ cytosol?
This is a semi-transparent fluid in which organelles are suspended and makes up 80% of the cell. Mainly water based.
44
what are inclusions?
These are chemical substances that store nutrients , secretory products and pigments granules.
45
Name energy transducer organelles
Mitochondria and chloroplast
46
Name information processor organelles
Nucleus and ribosomes
47
Name the different types of organelles
Secretory. Storage. information processors.
| energy transducers.
48
What are the types of endoplasmic reticulum?
Rough endoplasmic reticulum.
| smooth endoplasmic reticulum
49
What is the function of the rough endoplasmic reticulum?
1. protein synthesis with associated ribosomes and mRNA
2. Segregation of newly synthesised proteins
3. Chemical modification of proteins
50
What is the function of the smooth endoplasmic reticulum?
1. modifies chemicals imported into the cell
| 2. Lipid and steroid synthesis
51
what is the function of the Golgi complex?
1. Receives synthesise proteins from the endoplasmic reticulum
2. concentration, modification and final packaging of proteins.
3. Synthesis of cell wall polysaccharides
4. Stores proteins and enzymes of the cell
5. Forms secretory vesicles (storage and transport) and lysosomes (digestive processes of the cell)
52
What are the function of lysosomes?
1. Degradation of cell organelles
2. maintains the balance between synthesis, degradation and recycling of of cellular products
3. A major mechanism in which a starving cell may reallocate nutrients from unnecessary processes to more essential processes
53
what is the function of peroxisomes?
1. Detoxification.
2. The breakdown of fatty acid molecules to 2 carbon fragments and converted acetyl- CoA and fed back into cellular respiration
54
What is gluconeogenesis?
This is when sugars are synthesised from fatty acids until the seedling is mature enough to produce them by photosynthesis
55
what is the function of the vacuole?
Provide turgor in plants. Waste Disposal and Recycling. Storage of toxins. Pigmentation. Germination.
Attract pollinators.
56
what are plastids?
This is any pigmented cytoplasmic organelle found in plant cells and protist.
57
What are kinds of plastids?
Chromoplast and Leucoplasts
58
What is the function of chromoplast?
Attraction of pollinators and dispersal agents through floral and fruit colours
59
what is the function of leucoplast?
Specialised for storage
60
What is it important for cells to be small?
This allows for there to be a larger surface area that allows greater rate of exchange of resources and removal of waste products, while large cells have high rate of chemical activity but low rate of exchange
61
delete
delete.
62
What are the structures of prokaryote?
Plasma membrane, cell wall, capsule, cytoplasm, ribosomes, nucleoid, plasmid.
63
what are the different types of eukaryotic cell shape?
fixed - paramecium
| variable - white blood cells, amoeba
64
What maintains the eukaryotic cell shape - unicellular?
tough plasma membrane, exoskeleton
65
What maintains the eukaryotic cell shape - multicellular ?
cytoskeletons, plasma membrane, adjoining cells, external environment,
66
what is the function of the mitochondria?
This is the powerhouse of the cell. produces energy through cellular respiration like: Krebs cycle, electron transport system, B- oxidation of fatty acids.
67
What are the functions of the nuclear pores in the nucleus?
1. communication with cytoplasm
2. transport of ribosomes, nucleotides and proteins
3. Associated with rough endoplasmic reticulum
68
What are the functions of the nucleus?
Site of DNA storage, genetic control of metabolism, produces ribosomes and RNA
69
what are histones?
these are proteins involved in a range of activities including DNA replication and gene expression.
70
What are chromosomes?
These are highly condensed, visible strands of chromatin.
71
what are the functions of the extracellular matrix?
1. Cellular organization in tissues (binding)
2. Provide storage and anchorage for cells
3. Segregating tissues from one to another
4. Cell signalling (regulating intercellular communication and cell behaviour
5. Privides lubrication in joints
6. Influences the processes of growth and repair
7. Influences the physical properties of the tissues
72
what are cell adhesion molecules?
These are cell surface proteins that binds with other cells or extracellular matrix
73
What are the principle classes of cell adhesion molecules?
1. Cadherins - calcium dependent adhesion molecules
2. Immunoglobulin superfamily - attached to the membrane of the effector B cells
3. Selectins - initial attachment of leukocytes during inflammation
4. Mucins - coat many epithelial surfaces and is secreted into fuilds such as saliva e.g lubrication, cell signalling
5. Integrins - mediate cell to cell and cell matrix interaction and communication
74
What are cell junctions?
These are protein complexes that allow contact, adhesion and communication between neighbouring cells, cells and the extracellular matrix.
75
what are the types of Cell Junctions?
Tight junctions
Desmosomes
Gap/ Communicating junctions
76
Whats the structure and function of the middle lamella in the plant cell wall?
This adheres cell wall of adjoining cells and is formed from cell plate during cell division. It is made up Pectin- calcium and magnesium
77
What are the different cell transport mechanisms?
Molecular movement
transmembrane movement
mediated transport
Phospholipid movement
78
what is molecular movement?
This is the movement of molecules from an area of high concentration to an area of low concentration. this takes place via random kinetic (brownian) movement.
79
What are factors that affect the rate of movement of molecules?
size of particle, electrical charge, concentration gradient and thermal energy
80
What are the types of phospholipid movement?
Rotational movement - spinning in place
Lateral movement - moves side to side (rapid) allows fluidity of the cell
Transverse movement - phospholipids exchange places with each other. like top switch with bottom
81
What are the types of Passive transport processes?
Simple diffusion
Osmosis
Facilitated diffusion
82
What are the two types of active transport processes?
Endocytosis and exocytosis
83
What can DIFFUSE through the lipid bi layer?
Gases (Co2, N2, O2), Small uncharged polar molecules (ethanol), water,
84
What cannot DIFFUSE through the lipid bilayer?
Large polar uncharged molecules (Glucose), Ions (K+, Mg2, Ca2+, Cl-) Charged polar molecules (amino acids, ATP)
85
What affects osmosis movement?
Hydrostatic pressure and osmotic concentration
86
What is bulk flow?
Bulk flow is a process used by small lipid-insoluble proteins to cross the capillary wall.
87
What is solvent drag?
This is when solutes are dragged along with the passing water.
88
What are the types of proteins in facilitated diffusion?
Passive proteins and Carrier proteins
89
Whats the difference with passive and carrier proteins?
Carrier proteins need to be glucose activated and allows on molecule at a time while passive proteins just stay open.
90
What is mediated transport?
This is the transport of molecules via pumps or channels.
91
What are the different kinds of channels?
Ion channels and Gated channels
92
What are characteristics of Ion channels?
1. channels can be highly selective e.g some will transport -ve but not +ve
2. They exist in open and closed states
3. Transitions between open and closed states are regulated
93
What are the different classes of ion channels?
Ligand-gated channels - open and close in repsonse to the binding of specific chemicals
Voltage gated channels - open and close in response to the electrical potential across the membrane in which they are found.
94
What are the types of gated channels?
1. mechanical gated channels
| 2. Voltage-gated channels
95
What are mechanical gated channels?
mechanical stimulation of the operation ion channels e.g inner ear sensory cells of the cochlea (sound waves)
96
What are Voltage-Gated channels?
operates in neurons and muscle cells. channels open and close in response to changes
97
What are uniports?
these are carrier proteins that transport a single solute form one side of the membrane to another
98
What are coupled transporters?
these are carrier proteins that transport two or more solutes from one side of the membrane to another
99
What are symports?
these are carrier proteins that transport two different substances in the same direction
100
What are antiports?
these are carrier proteins that transport two different substances in opposing directions.
101
Explain primary and secondary active transport.
active transport utilizes membrane pumps.
| Primary directly harnesses ATP while secondary indirectly harnesses ATP
102
What is pinocytosis?
This is the ingestion of fluid material
103
What is phagocytosis?
This is the ingestion of solid material
104
What is vacuolisation?
This is the formation of vacuoles or vacuole-like structures. his usually takes place because of endocytosis when foreign objects after entering the cell would be surrounded by a vacuole/vesicle.
105
What is movement?
This is the use of chemical energy to apply force to a mass or change in position of a part or organ of an organism.
106
What is locomotion?
This is the change in position of a whole organism
107
What are the types of locomotion
Amoeboid, Ciliary/flagellar, Muscular
108
What are the types of intracellular movement?
Vesicular movement, Cytoplasmic streaming, Cell division
109
what are the components that facilitate intercellular movement?
Microfilaments, microtubules, motor proteins
110
what is the cytoskeleton?
This is a collection of thin long fibres which maintains cell shape, support cellular movement (positions and moves organism) facilitate the transport of substances in out and around the cell,
111
What are the components of the cytoskeleton?
Microfilaments, microtubules, intermediate filaments
112
What is the Microtubule organising centre?
This is the area near the nucleus where microtubules are assembled
113
What are the two types of microtubule organising centres?
Basal bodies - associated with the cilia and certain intercellular junctions in epithelial cells
Centrosomes - associated with animal cells
114
What are the functions of microfilaments?
Maintain shape
Changes in cell shape (animal cytokinesis)
muscular activity in concert with myosin filaments
115
What are the functions of intermediate filaments?
Stabilise cell structure (in desmosomes)
resist tensile forces
provide anchorage for cytoskeleton (in the base of the microvilli)
116
Describe the structure of microtubules
They are anchored at one side and grows on the others. they are polar with a plus end (fast growing) and a minus end (slow growing). the negative side is usually the anchoring point.
117
delete
delete
118
How does cilia and flagella move?
They move because of interactions of a set of microtubules (axoneme). this is done by sliding one of the microtubules past another
119
delete
delete
120
delete
delete
121
delete
delete
122
delete
delete
123
What is cytoplasmic streaming?
This is a circular Flow of cell cytoplasm around the vacuole and involves the interaction of actin filaments (microfilaments) with myosin. This occurs in plant cells.
124
How does amoeboid locomotion take place?
Polymerisation of actin molecules “pushes out” the pseudopodium/lamellipodium then The back end of the cell is drawn forward by contraction of the cell body due to interaction between actin and myosin
125
what are Pseudopodia?
extensions formed by conversion of cytoplasm
126
What are cilia and flagella?
These are outgrowths from the cell that arise from a cytoplasmic basal body beneath the cell membrane and extend to form axoneme
127
What is axoneme?
this is the central strand of a cilium or flagellum. It is composed of an array of microtubules, typically in nine pairs around two single central ones.
128
what's the difference with cilia and flagella?
```
Flagella:
• Longer
• Occur singly or in pairs
• Whiplash or tinsel
• Wave-like undulating beating / motion propagated from the base to the end
```
```
Cilia:
• Shorter
• Much more numerous
• One type
• Movement accomplished similar to a swimmer’s arm
```
129
What are the different types of flagellar?
The whiplash - is acute with an acute bend at the end
| The tinsel typed - is branched with many mastigonemes (extrusions) along it's axis
130
How does muscular movement take place?
Interactions between the contractile proteins (actin and myosin) results in shortening of muscle fibres which causes muscle contraction.
131
What is the order from largest to smallest in the muscle?
Muscle - muscle bundle - fascicle - muscle fibre/ muscle cell - myofibril - sarcomere - myosin, actin and z - line
132
How early do cells begin to differentiate?
as early as 8 - cell stage
133
What are micrometers and macromeres?
these are cells that from from cleavage of a ovum. micrometers are smaller portions while macromeres are larger portions.
134
what do micromeres and macromeres develop into?
Micrometers develop into the embryo while macromeres devlop into extra-embryonic membranes
135
What are the stages of development in animal cells?
1. Fertilization - zygote
2. Mitosis - 2, 4, 8 cells
3. Commitment - fate of cells become determined
4. Histogenesis - differentiation of cells
5. Morphogenesis - change in shape of embryo
136
What does totipotency mean?
This means that the cells carry the full set of genes and have the potential to become any adult cell and are considered indeterminate.
137
How does the level of potency change as the cells specialise?
totipotency - pluripotent - multi potency -specialization
138
What is are stem cells?
These are unspecializated cells that are able to reproduce itself and differentiate into various types of cells
139
What are the different types of cells?
Embryonic stem cells – totipotent
| Adult stem cells – pluripotent
140
Whats the difference with adult and embryonic stem cells?
```
Embryonic:
• Found in blastula/blastocyst (see later)
• Totipotent
• Can become any type of cell
Adult:
• Found in bone marrow
• Pluripotent
• Mainly can be transformed into different types of blood cells
```
141
How are embryonic stems cells isolated?
1. sperm and egg join
2. embryo develops for 5-7 days
3. remove inner cell mass
4. grow in dish
5. change conditions to stimulate cells to differentiate into a variety of cell types
142
How are induced pluripotent stem cells created?
1. Isolate cells form patient - grow in a dish
2. treat cells with reprogramming factors...wait 3 weeks
3. results in pluripotent stem cells
4. change conditions to stimulate cells to differentiate into a variety of cell types
143
How are embryonic stem cells created through therapeutic cloning?
1. Isolate cells from patient
2. remove nucleus from an egg cell
3. transfer nucleus from patients cell to the egg
4. egg cell reprogrammed the patients DNA
5. Stimulate cell to begin dividing and let it develop to blastocyst stage
6. isolate the inner cell mass from the blastocyst and grow it in a dish
144
Explain competency and restriction.
Cells at a certain stage are said to be competent because they can be influenced by the environment in which they develop. Once they differentiate they lose this competency and become restricted
145
What are histogenesis mechanisms that drive development and differentiation in cells?
1. cytoplasmic determinants in the egg
| 2. inducer molecules form other cellls
146
what is invagination and evagination?
evagination is for something to push out while invagination is for something to cave in. evagination and invagination is a result of contraction.
147
Explain how morphogenesis works.
As an organism develops it changes shape and organization. cell begin to differenciate and form specialised structures of organs int he body. Usually in animal development the cells begin to migrate other areas of the developing embryo. movement is large scale and involves large # of cells.
148
how are primary cell layers in the animal cell formed?
The outer ectoderm gives rise to the epidermis and epithelial structures in the adult while the inner endoderm gives rise to the lining of the gut.
149
What is a the mesoderm?
The mesoderm forms the muscles and associate structures in the adult and lines the space formed between the endoderm and ectoderm which is known as the coelom or body cavity.
150
What are the different types of animal tissue classification?
epithelial tissue, connective tissue, skeletal tissue, muscular tissue, blood tissue, nervous tissue.
151
What is the function of epithelial tissue?
* Covers body surface
* Skin, lining of the gut are examples of epithelial tissue –these have lot of wear and tear and therefore, have high rate of cell division
* Dandruff, Pap-smear test for cancer of the female reproductive tract is based upon the examination of shedding epithelial cells
* Lines hollow organs, body cavities, and ducts, e.g. lungs
* Forms glands, e.g. sweat glands, mammary glands
* Protection – Epithelium of the skin protects underlying tissue from mechanical damage, UV light, dehydration, invasion by bacteria
* Secretion - Secretes digestive enzymes in the intestines and absorbs the products of digestion
152
What is the function connective tissue?
Protects and supports the body and its organs; binds organs together; stores energy reserves as fats
153
What is the function of muscle tissue?
Responsible for movement and generation of force
154
What is the function of nervous tissue?
Initiates and transmits action potentials (nerve impulses) that help to coordinate body activities
155
What is the function of blood tissue?
Liquid tissue responsible for transport through the body (O2, CO2, food, ions, wastes, hormones, heat) and defence of the body
156
What are the different kinds of connective tissue?
Supportive connective tissue - Cartilage and Bone matrix
| Binding connective tissue - Tendons, ligaments, fibrous connective tissue
157
What are the different kinds of muscle tissues?
skeletal muscle, smooth muscle, cardiac muscle
158
What are the different kinds of nerve tissues?
Neurons, Glial cell
159
Where do all the blood cells originate from?
bone marrow
160
What the the different cells found in the blood?
* Red blood cells (RBCs) - Erythrocytes
* White blood cells (WBCs) - Leukocytes
* Platelets - Thrombocytes
161
What is the function for red blood cells?
Responsible for the transport of O2 and CO2.
162
what is the function of white blood cells?
Protect body from infection
163
What dow white blood cells consist of?
1. Lymphocytes
2. Monocytes - Monocytes leave the blood and become macrophages.
3. granulocytes
164
What are the different types of granulocytes?
* Neutrophils
* Eosinophils
* Basophils
165
What are the different kinds of lymphocytes?
* B lymphocytes(“B cells”)
| * T lymphocytes (“T cells”)- subtypes inflammatory T cells, cytotoxic T lymphocytes, helper T cells.
166
What are the different kinds of plant tissue?
* Meristematic • Protective • Parenchyma
| * Sclerenchyma • Collenchyma • Xylem • Phloem
167
What is meristem tissue?
These are small thin-walled cells with no central vacuole and no specialized features. it is located at the ends of stems and roots where growth takes place. The main function of meristematic tissue is mitosis.
168
What is protective tissue?
Protective tissue covers the surface of leaves and the living cells of roots and stems e.g lower and upper epidermis.
169
What are ground tissues?
* Parenchyma
* Collenchyma
* Sclerenchyma
170
What is the difference with Parenchyma, Collenchyma and Sclerenchyma?
Parenchyma is mainly for photosynthesis and storage. Sclerenchyma supports and strengthen non-expanding tissue, they are found in stems and leaf veins and are dead at maturity. Collenchyma provides strength for the plant found in the petiole/stalk.
171
how do cells communicate?
By sending and receiving signals and then converting them into responses .
172
What is extra cellular environment?
This is where cells pass their waste and receive nutrients. also this this where they receive majority of their chemical signals.
173
what are the different kinds of cell signals?
1. Autocrine signals - diffuse too and affect the cells that make them
2. Endocrine signals - molecules are released by cell/ organ and transported to the receptors on another cell by means of a transport system like the blood stream
3. Paracrine signals - signals diffuse to and affect nearby cells.
174
What are hormones?
These are signals that are sent to distant cells.
175
What is the signal transduction pathway?
this is from the signal’s affecting a receptor, to conveying a message to the cytoplasm , to the cell ‘s final response
176
What is a ligand?
A molecule that binds to a receptor site
177
What are the different kinds of ligands?
1. Ligands with cytoplasmic receptors: Small and non-polar ligands can diffuse across the phospholipid bilayer of the plasma membrane and enter the cell eg. Estrogen.
2. Ligands with plasma membrane receptors: Large or polar ligands cannot cross the plasma membrane eg. Insulin
178
What are ion channel receptors?
These ion channels act as “gates” allowing ions such as Na+, K+, Ca+, or Cl- to enter or leave the cell.
179
What are protein kinase receptors?
Some eukaryotic receptor proteins proteins become kinases when they are activated, they catalyze the transfer of a phosphate group from ATP. Phosphorylation can alter the conformation and activity of the target protein.
180
What are g protein linked receptors?
```
a class of signaling proteins with three
polypeptide subunits that are characterized by their ability to bind GDP and GTP
```
181
What are cytoplasmic receptors?
Are located inside the cell and bind to signals that diffuse across across plasma membrane. Binding to the signal ligand causes the receptor to change its shape so that it can enter the cell nucleus, where it acts as a transcription factor affecting gene expression.
182
What is direct transduction?
is the function of the receptor itself and occurs at the plasma membrane.
183
What is indirect transduction?
another molecule termed a second messenger mediates a further interaction between receptor and cell’s response.
184
What cells secrete hormones?
Endocrine cells
185
What are circulating hormones and paracrine hormones?
Hormones that diffuse directly into the blood and distributed throughout the body to target cells far away from site of release. while paracrine target cells near their release site
186
Whats the different with endocrine and exocrine glands?
Endocrine secretes without ducts exocrine secretes with ducts.
187
What is an autocrine function?
When a hormone influences the cell that releases it
188
what are the different chemical groups of hormones?
Peptide/polypeptide
Steroid hormones
Amine hormones
189
Describe steroid hormones
They are lipid soluble and easily dissolve in and pass through cell membranes. Steroid hormones are soluble in blood, they must be bound to carrier proteins in order to be transported to target cells.
190
Describe peptide/polypeptide hormones
These hormones tend to be water soluble and are easily transported in the blood, but cannot pass readily through lipid-rich cell membranes.
191
Describe Amine Hormones
Some amine hormones are water soluble and other are lipid soluble, mode of release differ
192
where are some hormones stored?
▪ Amino acid based hormones stored in membrane bound vesicles within cell cytoplasm.
▪ Fatty acid hormones accumulate in cytoplasm as clear lipid droplets or as lipid-protein complexes bound to the cell membrane.
193
Where are hormones destroyed?
1) at liver
2) by target tissue
3) excreted in urine
194
What is respiration?
Respiration is the breakdown of food material, either taken into the body or produced by the organism, to yield energy which is harnessed as chemical energy.
195
Describe the metabolism of glucose
Glucose is split to release electrons from the Hydrogen atoms which are used to reduce oxygen. The glucose metabolism pathway “traps” the stored energy from glucose in ATP molecules. In this process electrons are transferred from a high energy level to a lower one releasing free energy which is used to convert ADP to ATP.
196
What are the metabolic processes that has an important role in the harvesting of glucose?
Glycolysis, cellular respiration and fermentation
197
What are the components of respiration?
Glycolysis,
The Citric acid/Krebs/Citric acid or TCA cycle
The electron transport chain
198
What is glycolysis?
the breakdown of glucose to pyruvate in the absence of oxygen.
199
What is The Citric acid / Krebs / Citric acid or TCA cycle?
the conversion of pyruvate to acetyl CoA which enters a cycle and combines with oxaloacetate to give citrate which is broken down to release energy.
200
What is the electron transport chain?
which moves electrons from a high energy plain to a lower energy plain releasing free energy in the process
201
Explain the process and steps of glycolysis
1. ATP transfers a phosphate group to glucose.
2. The glucose is rearranged via isotopy to form fructose
3. Atp adds another phosphate to the fructose
4. the ring opens breaking the fructose group into two 3-carbon glyceraldehyde- 3 phosphate (G3P)
5. Two molecules of NAD+ are reduced into two molecules of NADH
6. Two phosphate groups are removed producing two atp molecules per molecule of glucose. then a pyruvate is produced.
202
What are the possible routes for pyruvate?
Go into anaerobic respiration or Krebs/ Citric acid/ Tricarboxylic acid cycle
203
What are the main fermentation processes?
1. Lactic Acid Fermentation
| 2. Alcohol Fermentation (occurs in yeast and bacteria)
204
How does lactic acid fermentation take place?
The Pyruvic acid formed during Glycolysis each gain a hydrogen from NADH.
The new hydrogen turn the Pyruvate into lactic acid and energy is released (which is used to form ATP).
Glucose → Pyruvic acid → Lactic acid + energy
205
How does alcohol fermentation take place?
In Fermentation the Pyruvate made during Glycolysis loses another carbon making carbon dioxide. The two sets of carbons left each gain a hydrogen from NADH. This turns the two carbon chains into Ethyl Alcohol.
206
What are the cellular locations for energy pathways in eukaryotes?
Cytoplasm
- Glycolysis
- Fermentation
Inside mitochondria
(inner membrane)
- electron transport chain
-Krebs cycle
(matrix)
- citric acid cycle
- pyruvate oxidation
207
What are the cellular locations for energy pathways in prokaryotes?
In cytoplasm
- glycolysis
- fermentation
- citric acid cycle
On plasma membrane
- pyruvate oxidation
- electron transport chain
208
Explain the processes of the Krebs Cycle
1. The cycle begins with the conversion of pyruvate to acetyl CoA. 3 carbon molecule from glycolysis is broken down to a 2 carbon molecule. Yielding 1 NADH from NAD+ for each pyruvate molecule.
2. The three carbon pyruvate molecule is oxidized and decarboxylated to form two carbon acetyl group, which is attached to co-enzyme A as acetyl CoA
3. The acetyl CoA (2 carbon) combines with Oxaloacetate (a 4- carbon molecule) to give citrate, a 6 –carbon molecule
4. The CoA part of the acetyl CoA is released to combine with a new acetyl group when another molecule of pyruvate is oxidized.
5. Two of the six carbons are removed from citrate and oxidized to CO2.
6. Oxaloacetate is regenerated
209
What does Krebs cycle use and produce?
Oxaloacetate + Acetyl CoA + 3H2O + ADP + Pi + 3(NAD +) + FAD
⇨⇨⇨⇨
Oxaloacetate+ 2CO2 + CoA+ ATP+ 3NADH+ + 3(H+) + FADH2
210
What is the net gain of Krebs cycle form one molecule of glucose?
▪ Each pair of electrons, ie each NADH + H+ generates 3 ATP molecules
▪ Total NADH + H+ from one molecule of glucose = 6 6 X 3 = 18 molecules of ATP formed
▪ Each FADH2 forms 2 ATP molecules (it enters the ETC later)
▪ Number of ATP molecules formed = 2
2X2=4
▪ Plus 2 ATP formed from GTP
▪ Plus 2 molecules of NADH + H+ from conversion of Pyruvate to Acetyl CoA = 6 ATP (2X3)
▪ Total ATP formed from one molecule of Glucose in TCA cycle = 30
211
What is the chemiosmotic theory?
The flow of electrons through a series of membrane associated carrier molecules in the mitochondrion results in the transport of protons (H+) from the matrix of the mitochondrion through proton pumps to the intermembrane space
212
What does NAD stand for?
Nicotinamide Adenine Diphosphate
213
What is brown fat?
The tissues in which this uncoupled process is found are specialised for heat production and are called brown fat
Brown fat has a high concentration of mitochondria and a rich blood supply. The movement of H+ ions is decoupled from ATP production by a protein called thermogenin.
214
What is the uncoupling of proton movement?
An uncoupler or uncoupling agent is a molecule that disrupts oxidative phosphorylation in prokaryotes and mitochondria or photophosphorylation in chloroplasts and cyanobacteria by dissociating the reactions of ATP synthesis from the electron transport chain.
215
What is non-shivering thermogenesis?
Sulzer’s vein carries warmed blood from the brown fat area back to the heart. Heats the animal up and increases metabolic rate
216
What is photosynthesis?
is a metabolic process by which the energy of sunlight is captured and used to convert carbon dioxide and water in carbon hydrate sugars and oxygen.
217
What are the different light-independent pathways that reduce Carbon dioxide?
the Calvin cycle, C4 photosynthesis and the crassulacean acid metabolism.
218
Where does the light capturing reaction of photosynthesis take place?
In the thylakoids
219
where are thylakoids located?
in the grana
220
where does The series of reactions by which the captured light energy is used to synthesize carbon-containing compounds occur?
in the stroma (the area surrounding the thyadkoids)
221
What happens during period of abundant rate of photosynthesis?
Some of the carbohydrates are stored as temporarily in the chloroplast as grains of starch.
222
What happens to grains of starch at night?
At night they are converted into sucrose and used to supply parts of the plant.
223
What is the relationship with the energy of a photon and its wavelength?
long wavelength = low energy of photon
| short wave length = high energy photon
224
What are the main photosynthetic pigments?
- the chlorophylls
- the carotenoids
- the phycobilins
225
What are the different kinds of chlorophylls?
1. Chlorophyl a - Present in all photosynthetic eukaryotes and in the cyanobacteria. Essential for the oxygen generating photosynthesis
2. Chlorophyl b - This an accessory pigment [pigment is not directly involved in photosynthetic energy transduction but serves to broaden the range of light that can be used in photosynthesis]
3. Chlorophyl c - Takes the place of chlorophyll b in some groups of algae e.g.
brown algae
226
Describe carotenoids.
--- A source of vitamin A
--- Anti-oxidant properties [preventing oxidative damage to the chlorophyll molecules by light]
--- Used in capture of energy which is transferred to chlorophyll a
--- These pigments cannot substitute chlorophyll in the
photosynthesis.
(found when plants enter fall and turn orange or red)
227
Describe phycobilins
- -- Accessory pigment
| - -- Found in cyanobacteria and red algae
228
What are the two major reactions of photosynthesis?
energy transduction and carbon fixation reactions
229
What is the light reaction/energy transduction reaction of photosynthesis?
▪ H2O splits →O2 + ATP + NADPH2
▪ ATP is formed
▪ NADP reduced to NADPH2
▪ Takes place in the thylakoids
230
What is the carbon fixation reaction of photosynthesis?
▪ ATP + NADPH2 + CO2 C6H12O6
▪ Conversion of CO2 into organic compounds is known as carbon fixation OR CO2 fixation
▪ Does not require light energy (but depends upon the products from the light reaction)
▪ Includes the Calvin cycle
▪ Takes place in the stroma
231
Whats the relationship of the light dependent and the light independent reaction?
light dependent reaction- splits water and produces oxygen while producing oxygen and atp
light dependent reaction - consumes atp and nadph and produces glucose, adp and nadp+
232
what does photosystem 1 do?
uses light energy to reduce NADP+ to NADPH + H+ (is almost entirely in the stroma thylakoids and at the margins or outer portions of either side of the grana thylakoids). Can operate independently
233
What does photosystem 2 do?
uses light energy to oxidize water molecules, producing electrons , protons H+ and O2. (located primarily in the grana thylakoids). Also equires photons that are somewhat more energetic (shorter wavelength) than those required by photosystem I.
234
what is the wavelength of photosystem 1 and 2?
Photosystem 1 = P680 (wavelength of 680 nm)
| photosystem 2 = p700 (wavelength of 700nm)
235
what is photophosphorylation?
Photophosphorylation is the conversion of ADP to ATP using the energy of sunlight by activation of PSII. This involves the splitting of the water molecule in oxygen and hydrogen protons (H+), a process known as photolysis.
236
What is cyclic photophosphorylation?
The photophosphorylation process which results in the movement of the electrons in a cyclic manner for synthesizing ATP molecules.
237
Where does carbon fixation/reduction take place?
occurs in the stroma of the chloroplast by means of a series of reactions called the Calvin cycle.
238
What is carbon fixation/ reduction?
this is the process by which inorganic carbon is converted to organic compounds by living organisms.
The ATP and NADPH generated by the light reactions are used to fix and reduce carbon and to synthesize simple sugars.
239
Explain the process of the Calvin cycle
1. Carbon dioxide combines with RuBp (ribulose 1, 5 biphosphate this results in the formation of 3pg
(3- phosphoglyceric acid)
2. 3-phosphoglycerate is reduced to 3 phosphoglceraldehyde (PGAL) in a two step reaction requiring ATP and NADPH + H+
3. Five of the six molecules of glyceraldehyde 3-phosphate are used to generate 3 molecules of ribulose 1,5-bisphosphate, which is the starting material in the cycle. while one-sixth is used to make sugars
240
What is the equation for the production for glyceraldehyde 3- phosphate?
3CO2 + 9ATP + 6NADPH + 6H+ Glyceraldehyde 3-phosphate + 9ADP + 8Pi + 6NADP + 3H2O
241
What are the processes that connect light reactions with CO2 carbon fixation pathway?
Light induced Ph and light induced electron transport
242
What does light induced electron transport do?
reduces disulfide bridges in four of the Calvin cycle enzymes, thereby activating them.
243
What does light induced ph do?
changes in the stroma activate some Calvin cycle enzymes. Proton transfer from the stroma in the thylakoid lumen causes an increase in pH of the stroma that favors the activation of rubisco.
244
What is photorespiration?
Photorespiration is a wasteful pathway that occurs when the Calvin cycle enzyme rubisco acts on oxygen rather than carbon dioxide.
245
What is the reaction for rubisco binding with 02?
When Rubisco binds with O2 the catalysis results in the formation of a poison phosphoglycolate:
RuBP + O2 → phosphoglycolate + 3-phosphoglycerate (3PG)
246
Explain the processes of photorespiration?
1. in the Chloroplasts stroma RuBp reacts with O2. Glycolate formed.
2. Glycolate diffuses into the peroxisome, where it is converted to glycine
3. glycine moves to the mitochondrion and is converted to serine releasing Co2
4. Serine moves back to the peroxisome and is converted to glycerate.
5. Glycerate moves to the chloroplast where it is converted to 3pg and enters the Calvin cycle.
247
How are C4 and C3 plants distinguishable based on how they fix carbon?
C3 first product of fixation is a three while C4 is 4 carbon molecules
248
examples of C4 plants?
maize, sugarcane, callaloo, corn
249
Examples of C3 plants?
Wheat, rice, Oats, cotton, ptotatoes
250
Why do C3 plants undergo photorespiration but C4 doesnt?
1. In C4 the cells of the mesophyll are full of chloroplast containing rubisco. On a hot day when the stomata are closed, rubisco acts as an oxygenase as well as a carboxylase and photorespiration occurs.
2. On a hot day C4 plants partially closes their stomata to conserve water but the rate of photosynthesis does not fall. C4 plants have evolved a mechanism that increases the concentration of CO2 around the rubisco enzyme while at the same time isolating the rubisco from the atmosphere O2. the light-dependent reactions and the Calvin cycle are physically separated, with the light-dependent reactions occurring in the mesophyll cells and the Calvin cycle occurring in special cells around the leaf veins. These cells are called bundle-sheath cells.
251
How does C4 plants mechanism work?
1. Atmospheric Co2 is fixed in the mesophyll cells to form a simple,4-carbon organic acid (oxaloacetate). This step is carried out by a non-rubisco enzyme, PEP carboxylase, that has no tendency to bind O2.
2. Oxaloacetate is then converted to a similar molecule, malate, that can be transported in to the bundle-sheath cells. Inside the bundle sheath, malate breaks down, releasing a molecule of Co2.
3. Co2 is then fixed by rubisco and made into sugars via the Calvin cycle, exactly as in C3 photosynthesis.
252
What are the advantages of PEP carboxylase?
1. It does not have oxygenate activity.
| 2. It fixes CO2 even at very low CO2 levels
253
Examples of CAM plants?
Cactus, pineapples, Spanish moss
254
What does Cam stand for?
crassulacean acid metabolism
255
How does CAM plants and Calvin cycle work?
the initial CO2 fixation and the Calvin cycle are separated in time rather than space.
1. At night it is cooler and water loss in minimized, the stomata open. CO2 is fixed in mesophyll cells to form the 4 carbon compound of oxaloacetate, which is converted to malate and stored in the vacuole.
2. During the day, when the stomata close to reduce water loss, the accumulated malate is shipped to the vacuole to the chloroplast, where its decarboxylation supplies the CO2 for the Calvin cycle, and the light reactions supply the necessary ATP and NADPH.
256
What is Cell reproduction?
The process by which a cell duplicates itself for growth and reproduction of the given organism. Helps with growth and repair of tissues.
257
What are events that take place in cell division?
1. Cell division signals
2. DNA replication
3. DNA segregation
4. Cytokinesis
258
Explain cell division signals.
One or more signals are required to initiate cell division. The signals may originate from inside or outside of the cell.
259
explain DNA replication
the dividing cell ‘s genetic material DNA must be duplicated so that each of the two new cells will have a full complement of genetic information.
260
Explain DNA segregation
the replicated DNA must be distributed appropriately to the two daughter cells, so that each receives a copy of every chromosomes.
261
Explain cytokinesis.
the cytoplasm must divide to form the two new cells, each surrounded by a cell membrane and a cell wall in organisms that have one.
262
Which regions of prokaryotic chromosome play functional roles in cell reproduction?
1. ori: the site where replication of the circular chromosome starts (origin of replication)
2. ter: the site where replication ends (terminus of replication)
Replication begins at the ori site and moves bidirectionally toward the ter site.
263
What are the major differences between prokaryotes and eukaryotes DNA replication?
1. Eukaryotes DNA replication starts at numerous origins of replication, not at just one in prokaryotes.
2. DNA replication in eukaryotes is usually limited to part of the period between cell divisions and does not overlap with segregation of DNA into daughter cells
264
What are the phases of the cell cycle?
There are four phases.
G1, S (DNA synthesis), G2, M (mitosis)
G1, S, G2 makes up interphase.
265
What are cyclin-dependent kinases or CDKs?
kinase catalyzes the transfer of a
| phosphate group from ATP to target a protein in phosphorylation
266
How does CDK interact with G1/S cyclin?
CDK catalyzes the phosphorylation of a protein called retinoblastoma protein. In many cells RB act as an inhibitor of the cell cycle at the restriction point. To begin the S phase the cell must pass the RB block. Without the RB the cell cycle can proceed to G2 and subsequently M phase.
267
How can you regulate CDKs?
An effective way to regulate CDKs is to regulate the presence or absence of cyclins
268
What are cell cycle checkpoints?
These are signalling pathways where CDKs act that regulate cell progress.
269
How many cell cycle checkpoints are in a cell?
Four for each phase.
270
What are the phases of mitosis?
1. Prophase - condensation of chromosome; spindle assembly
2. Prometaphase - nuclear envelope breakdown; chromosome attachment to spindle
3. Metaphase - alignment of chromosomes at metaphase plate. middle of cell
4. Anaphase - Separation of sister chromatids; migration to poles
5. Telophase - Chromosomes decondense ; nuclear envelope reforms
6. Cytokinesis - Cell separation; cell membrane or cell wall formation
271
What are centrosomes?
Centrosomes are organelles which serve as the main microtubule organizing centers for animal cells. Before the spindle is formed, its orientation is determined by the centrosome, an organelle in the cytoplasm. During S phase the centrosome duplicates, and at the beginning of prophase the two centrosomes separate from one another, moving to opposite ends of the nuclear envelope.
272
What are the groups of microtubules?
Polar microtubules - form the framework of the spindle and run from one pole to the other
Kinetochore microtubules - attachment of chromosomes to the spindle microtubules, monitoring those attachments and helping to power the movements of chromosomes on the spindle.
273
What controls the separation of chromatids?
M phase cyclin CDK, which activates another protein complex called the anaphase-promoting complex.
274
What mechanisms operate the movement of chromosomes to opposing poles?
1. The kinetochores contain molecular motor proteins which use energy from ATP hydrolysis to do the work of moving the chromosomes along the microtubules.
2. The kinetochore microtubules, shorten, drawing the chromosome towards the poles.
3. The centrosomes move apart aiding in separation.
275
How does cytokinesis divide the cell?
A contractile ring composed of microfilaments of actin and associated myosin, form a ring on the cytoplasmic surface of the cell membrane. These two proteins interact to produce a contraction, pinching the cell in two.
276
Whats the difference with animal and plant cytokinesis?
Animal cells have a contractile ring while plants have a cell plate.
277
Whats the difference with meiosis and mitosis?
Mitosis makes things that are genetically identical while mitosis produces things that are genetically variated.
mitosis can be asexual and sexual reproduction while meiosis is only sexual.
278
What are somantic cells?
multicellular organisms’ cells not specialized for reproduction are referred to as somatic cells, each containing two sets of chromosomes, in pairs.
279
What are the stages of meiosis 1?
1. Early prophase 1 - The chromatin begins to condense
2. Mid-prophase 1 - synapsis aligns homologs and replicated chromosomes condense further
3. Late prophase- prometaphase - The chromosome continue to condense and shorten genetic exchange between non sister chromatids
4. Metaphase 1 - chromatids line up at the metaphase plate
5. Anaphase 1 - moves to oppose poles in the cell
6. Telophase - Chromosomes gather into nuclei and the original cell begins to divide
280
What are the stages of meiosis 2?
Its the same as mitosis only difference is that it happens with two cells instead of just one. cause at the end meiosis produces four cells endnote just one.
281
Are the end products of meiosis haploid or diploid?
They are haploid
282
What is crossing over in meiosis?
an exchange of genetic material between non sister chromatids on homologous replicated chromosomes
283
What is chiasmata?
the regions having the attachments between chromatids take on an X appearance
284
What are recombinant chromatids?
the exchange of genetic material between the maternal and paternal
285
What is independent assortment?
how different genes independently separate from one another when reproductive cells develop.
286
What is a reasons for genetic diversity in meiosis?
Crossing over and independent assortmore
287
What is non-disjunction?
the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.
288
What are aneuploidy?
is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46.
289
What is translocation?
a piece of a chromosome may break away and become attached to another chromosome.
