Biology - things that need polishing Flashcards
1
Q
What is the maximum magnification that can be achieved by a light microscope?
A
1500x
2
Q
What is the maximum magnification that can be achieved by a transmission electron microscope?
A
500 000 x
3
Q
What is the maximum magnification that can be achieved by a scanning electron microscope?
A
100 000 x
4
Q
Define resolution.
A
The ability to see two objects that are close together as separate objects and the ability to see detail.
5
Q
What is the magnification calculation?
A
Magnification = image size / actual size
6
Q
What is the maximum resolution of a light microscope?
A
200nm
7
Q
What is the function of xylem tissue?
A
Xylem is one of the two types of transport tissue in vascular plants.
The function is to transport water, and some nutrients, from roots to shoots and leaves.
8
Q
What is the function of lignin?
A
- Lignin strengthens & thickens the xylem wall.
- Waterproofs the wall
- Improves adhesion of water molecules.
- Its spiral pattern allows flexibility, stretching & movement
9
Q
What is the function of bordered pits?
A
To allow water and minerals to pass into the cells and other vessels and to bypass blockages.
10
Q
Define an organ.
A
A group of tissues that perform a specific function or group of functions.
11
Q
Define a tissue.
A
A group of cells of one or more types working together with common or the same function.
12
Q
How does the structure of arteries and veins differ?
A
Arteries have:
- no valves
- endothelium / tunica intima is folded
- more muscle / elastic tissue / tunica media
- more collagen / tunica externa
13
Q
What is the name of the cell type of the walls of the capillaries over which exchange occurs?
A
Capillaries have one layer of cells - the tunica intima where diffusion and exchange of materials takes place.
14
Q
Where does the carotid artery take blood?
A
The carotid artery takes blood to the brain.
15
Q
Where do the brachial arteries take blood?
A
The brachial arteries take blood to the arms.
16
Q
Where does the iliac artery take blood?
A
The iliac artery takes blood to the lower limbs.
17
Q
Where does the thoracic artery take blood?
A
The thoracic artery takes blood to the thorax where it differentiates into the hepatic, renal and gastric arteries.
18
Q
What are the three distinct layers that make up the blood vessels?
A
- tunica intima
- tunica media
- tunica externa
19
Q
What is the tunica media comprised of?
A
The tunica media is comprised of smooth muscle.
20
Q
What is the tunica externa comprised of?
A
The tunica externa is comprised of connective tissue.
21
Q
Explain the mechanism of inspiration.
A
- diaphragm / intercostal muscles contract
- diaphragm moves down
- ribs move upwards and outwards
- volume of thorax increased
- pressure inside thorax falls to below atmospheric pressure (so air enters lungs)
22
Q
How many strands is DNA?
A
DNA is double stranded.
23
Q
How many strands is RNA?
A
RNA is single stranded.
24
Q
What sugar is found in DNA?
A
The pentose sugar deoxyribose is found in DNA.
25
What sugar is found in RNA?
The pentose sugar ribose is found in RNA.
26
What are the bases in DNA?
Adenine, thymine, cytosine and guanine.
27
What are the bases in RNA?
Adenine, uracil, cytosine and guanine.
28
What are the types of RNA?
Messenger, transfer and ribosomal
29
Which type of RNA is involved in transcription?
mRNA is involved in transcription.
30
Which type of RNA is involved in translation?
tRNA is involved in translation.
31
A triplet of bases on DNA or mRNA is known as what?
A triplet of bases on DNA or mRNA is known as a codon.
32
A triplet of bases on tRNA is known as what?
A triplet of bases on tRNA is known as the anti-codon.
33
Where does transcription take place?
Transcription takes place in the nucleus.
34
Outline the process of transcription.
* The gene coding for the protein untwists then unzips
* H-bonds between the strands break
* Free RNA nucleotides form complementary base pairs with one strand of DNA bases
* Weak hydrogen bonds form between base pairs
* Sugar phosphate bonds form between RNA nucleotides
* mRNA strand is synthesized
* mRNA peels off the DNA and moves out of the nucleus into the cytoplasm
35
Where does translation take place?
Translation takes place in the ribosomes.
36
Outline the process of translation.
* Ribosomes are the site of protein synthesis
* mRNA strand attaches to a ribosome
* tRNA molecules transport specific amino acids to the ribosome
* each mRNA codon codes for a specific amino acid
the anti-codons and codons match up and form complementary base pairs
* peptide bonds form between the adjacent amino acids to form the polypeptide
37
What is the parasite responsible for malaria?
Plasmodium
38
What is the vector for malaria?
FEMALE Anopheles mosquitos
39
Where does Malaria replicate within the body?
Malaria replicates within the hepatocytes & red blood cells.
40
Where do the asexual stages of the Malarial life cycle take place?
In the red blood cells.
41
Where does the sexual stage of the Malarial life cycle take place?
In the stomach of the Anopheles mosquito.
42
Are B cells a part of the adaptive or innate immune system?
B cells are a part of the adaptive immune response.
43
Are T cells a part of the adaptive or innate immune response?
T cells are a part of the adaptive immune response.
44
Are dendritic cells a part of the adaptive or innate immune response?
Dendritic cells are a part of the innate immune response.
45
Are macrophages a part of the innate or adaptive immune response?
Macrophages are a part of the innate immune response.
46
What two types of cells can T cells differentiate into?
T cells can differentiate into T killer cells and T helper cells.
47
What are the major cells in the humoral immunity?
B cells are the major cells in humoral immunity.
48
What are the major cells in cell-mediated immunity?
T cells are the major cells in cell-mediated immunity.
49
Which cells can act as antigen presenting cells?
Dendritic cells and macrophages.
50
Which cells try to 'eat' the pathogen?
Phagocytes will phagocytose the pathogen.
51
To which cells do antigen presenting cells present their antigens?
Antigen presenting cells present antigens to the cells of the adaptive immunity.
52
What type of bond forms between two carbohydrate monomers?
A glycosidic bond forms between two carbohydrate monomers.
53
How many carbons are there in galactose?
Six carbons
54
How many carbons are there in fructose?
Six carbons
55
A disaccharide of glucose and fructose makes which sugar?
Sucrose
56
A disaccharide of two glucose monomers makes which sugar?
Maltose
57
A disaccharide of glucose and galactose makes which sugar?
Lactose
58
What is the function of sucrose?
Transport carbohydrates in plants
59
How is maltose obtained?
Maltose is formed from the digestion of starch
60
Which type of glucose is starch made from?
Starch is made from alpha glucose molecules.
61
Which type of glucose is glycogen made from?
Glycogen is made from alpha glucose.
62
What type of glucose is cellulose made from?
Cellulose is made from beta glucose.
63
Where is pepsin found?
Pepsin is only found in the stomach.
64
What does pepsin digest?
Pepsin digests protein.
65
Where is amylase found?
Amylase is found in the mouth.
66
What does amylase break down?
Amylase breaks down starch.
67
What does lipase break down?
Lipase breaks down fats.
68
What affects the shape of the enzymes active site?
pH and temperature can cause permanent damage to an enzymes active site.
69
What is competitive inhibition of enzymes?
Competitive inhibition involves a molecule that is not the substrate binding to the active site.
70
What is non-competitive inhibition of enzymes?
Non-competitive inhibition involves a molecule that is not the substrate binding to the enzyme away from the active site which causes a change in the active site no longer making it specific for its substrate.
71
Give examples of non-competitive inhibitors.
* cyanide
* mercury
* silver
72
What is feedback inhibition?
When the end product of the the enzyme reaction can bind to the active site blocking further reactions from occuring.
73
What does lactase break down?
Lactase breaks down lactose into glucose and galactose.
74
What does catalase break down?
Catalase breaks down hydrogen peroxide into water and oxygen.
75
What does the enzyme glycogen synthase do?
Glycogen synthase catalyses the formation of glycosidic bonds between glucose molecules.
76
What does the enzyme ATPase do?
ATPase breaks down ATP into ADP, producing energy.
77
What are endotherms?
Endotherms are animals that maintain their own body temperature.
78
What is the lock-and-key hypothesis?
The lock-and-key hypothesis states that the enzymes active site and the substrate fit together like a lock and key as the active site is specific for the substrate.
79
What is the induced fit hypothesis?
The induced fit hypothesis states that the substrate and the enzyme active site are not exactly complementary but the active site changes shape slightly when in contact with the substrate to make them fit together better.
80
What are the two categories of symbiosis?
* parasitism
| * mutualism
81
What is parasitism?
One species, the parasite, benefits at the expense of the other species, the host.
82
What is mutualism?
Both species benefit from the relationship.
83
What makes an effective parasite?
An effective parasite will not kill its host entirely.
84
What is biodiversity?
Biodiversity refers to the variety of species found in an ecosystem.
85
What are the three measurable aspects of biodiversity?
* genetic diversity
* species diversity
* ecosystem diversity
86
How many kingdoms are there in biology?
Five kingdoms.
87
What are the five kingdoms in biology?
* Animalia
* Plantae
* Fungi
* Protista
* Monera
88
What is artificial selection?
Artificial selection is the intentional reproduction of individuals in a population that have desirable traits. In organisms that reproduce sexually, two adults that possess a desired trait — such as two parent plants that are tall — are bred together.
89
What divides the larynx from the oesophagus?
The epiglotis divides the two. The epiglotis covers the larynx when we swallow.
90
What is the point where the trachea branches into the lungs called?
The carina of the trachea.
91
How many lobes make up the right lung?
| and what are they?
Three lobes make up the right lung.
The superior lobe
The middle lobe
The inferior lobe
92
How many lobes make up the left lung?
| and what are they?
Two lobes make up the left lung.
The superior lobe
The inferior lobe
93
What is the function of smooth muscle in the bronchioles?
Allows the bronchioles to contract.
94
Why do we have white blood cells such as macrophages in our lungs?
Stops inhaled pathogens from invading any further.
95
What is a type 1 alveolar cell?
Simple squamous epithelial cell that allows for exchange of gas.
96
What are the type II alveolar cells?
Secrete surfactant to reduce surface tension in the cells.
97
What characterises emphysema?
The destruction of the alveoli through the breakdown of elastic fibres by proteases secreted by immune cells.
98
What is the main cause of emphysema?
Smoking.
99
How are healthy alveoli protected from proteases?
Healthy alveoli secrete anti-proteases.
100
What are the major proteases that are secreted into the lungs?
Elastase and matrix metaloprotease.
101
Why is it hard to breathe out with emphysema?
Due to the loss of elastic fibres in the alveoli they lose their recoil system so air becomes trapped within them.
102
Give an example of a single-celled fungus.
Yeast is a single-celled fungus.
103
What is the cell wall of fungi made of?
Fungi have a cell wall made of chitin.
104
How are multicellular fungi organised?
Organised into a mycelium - which is made from thread-like structures called hyphae.
105
How do fungi gather their nutrition?
Saproptrophic nutrition.
- They secrete enzymes onto their food so that digestion happens outside the fungal cells. They then absorb the digested organic products.
106
What can fungal cells store carbohydrates as?
Fungal cells can store carbohydrates as glycogen.
107
What is mycelium?
The network of hyphae produced by a fungus.
108
What are hyphae?
Fine, branching, thread-like filaments produced by fungi.
109
What is saprotrophic nutrition?
A type of feeding in which digestive enzymes are secreted outside the cell onto food material, followed by absorption of the products.
110
Is secretion an active or passive process?
Secretion is an active process.
111
Is excretion an active or passive process?
Excretion is a passive process.
112
What is the medical term for high blood sugar?
Hyperglycaemia.
113
What is the medical term for low blood sugar?
Hypoglycaemia.
114
When blood sugar is too high, which hormone does the pancreas secrete?
Insulin is secreted when blood sugar is too high.
115
When blood sugar is getting too low, which hormone does the pancreas secrete?
Glucagon is secreted when blood sugar is getting too low.
116
In which type of diabetes does the body not produce any insulin?
In Type I Diabetes the body doesn't produce any insulin.
117
In which type of diabetes does the body produce insulin, but the receptors on the cells are no longer as sensitive to it?
In Type II Diabetes the cells are no longer as sensitive to insulin.
118
What does the pancreas secrete?
* digestive enzymes into the pancreatic duct to the duodenum
* bile into the bile duct to the duodenum
* secretes insulin and glucagon into the bloodstream
119
What do the pancreatic acine synthesise and secrete?
The pancreatic acine synthesise and secrete digestive enzymes.
120
What type of cells in the Islets of Langerhans secrete glucagon?
The alpha cells secrete glucagon.
121
What type of cells in the Islets of Langerhans secrete insulin?
The beta cells secrete insulin (and amylin)
122
What is secreted by the alpha cells in the islets of Langerhans?
Glucagon is secreted by alpha cells in the Islets of Langerhans.
123
What is secreted by the beta cells in the Islets of Langerhans?
Insulin is secreted by beta cells in the Islets of Langerhans.
124
What is secreted by the delta cells in the Islets of Langerhans?
Somatostatin is secreted by the delta cells in the Islets of Langerhans.
125
What is the function of somatostatin?
Somatostatin regulates the secretion of other pancreatic hormones.
126
What percentage of cells in the Islets of Langerhans are delta cells?
10% of cells in the Islets of Langerhans are delta cells.
127
What percentage of cells in the Islets of Langerhans are beta cells?
60% of cells in the Islets of Langerhans are beta cells.
128
What is the function of amylin?
Amylin slows down gastric emptying.
129
What percentage of cells in the Islets of Langerhans are alpha cells?
25% of cells in the Islets of Langerhans are alpha cells.
130
What effect does glucagon have on skeletal muscle?
Glucagon has no effect on skeletal muscle because there are no glucose receptors in skeletal muscle.
131
What effect does glucagon have on adipose tissue?
* Promotes the breakdown of triacylglycerol (TAG) into glycerol and fatty acids.
* Fatty acids travel to the liver where glucagon promotes their transfer into ketone bodies
* ketone bodies can be used as a source of fuel during fast for the brain and skeletal muscle
132
What effect does glucagon have in the liver?
Promotes gluconeogenesis
glycerol --> glucose-6-phosphate --> glucose
glycogen --> glucose-6-phosphate --> glucose
Proteins in the liver can be converted into amino acids which can also be fed into gluconeogenesis
(muscles can also provide these amino acids for gluconeogenesis)
133
What type of hormone is glucagon?
Glucagon is a peptide hormone.
134
What type of receptor does glucagon bind to?
Glucagon binds to a G-protein coupled receptor.
135
What effect does insulin have on the liver during the fed state?
Insulin promotes the uptake of glucose to the liver
Promotes the conversion of glucose to glycogen
Conversion of glucose alone pathway to triacylglycerols which can be stored as VLDLs in adipose tissue
Insulin promotes proteogenesis
136
TRUE or FALSE
| Fats are absorbed from the blood?
FALSE!
| Fats are absorbed from the lymphatic circulation.
137
Define autotroph
An autotroph is an organism that is able to make its own 'food' from simple inorganic substances such as carbon dioxide or light energy.
138
What is a trophic level?
A trophic level is an organisms position in the food chain.
139
Define the carrying capacity.
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water, and other necessities available in the environment.
140
What is interspecific competition?
Interspecific competition is a form of competition in which individuals of different species compete for the same resource in an ecosystem (e.g. food or living space).
141
What is intraspecific competition?
Intraspecific competition is where members of the same species compete for limited resources.
142
What are Hox (or Homebox) genes?
Hox genes (a subset of homeotic genes) are a group of related genes that control the body plan of an embryo along the cranio-caudal (head-tail) axis.
143
What does a chi-squared analysis tell us?
Chi-squared analysis tells us how likely it is that an observed distribution is due to chance.
144
What type of data is a chi-squared test designed to analyse?
A chi-squared test is designed to analyse categorical data.
145
How are the degrees of freedom calculated for a chi-squared table?
(number of rows - 1) x (number of columns - 1)
146
What are the columns, from left to right, in a chi-squared table?
```
observed
expected
(O - E)
(O - E)²
(O - E)² / E
```
147
When do you reject the null hypothesis?
If x² is greater than 0.05 (the level of significance) the null hypothesis is rejected.
148
How does glucose become triose phosphate?
Glucose is phosphorylated and hydrolysed to two molecules of triose phosphate
149
How does triose phosphate become pyruvate?
The two molecules of triose phosphate are each phosphorylated again and oxidised to pyruvate.
150
Why does phosphorylation occur during glycolysis?
Phosphorylation occurs so the glucose is activated and it is an investment of ATP.
151
What are the overall products of glycolysis?
2x ATP, 2x reduced NAD, 2x pyruvate.
152
How does pyruvate become acetyl coenzyme A in the link reaction?
* pyruvate is decarboxylated by pyruvate decarboxylase
* & dehydrogenated by pyruvate dehydrogenase to form acetate
* acetate is accepted by coenzyme A
153
Which enzyme decarboxylates pyruvate in the link reaction?
pyruvate decarboxylase decarboxylates pyruvate.
154
Which enzyme dehydrogenates pyruvate in the link reaction?
Pyruvate dehydrogenase dehydrogenates pyruvate
155
What is the first step of the krebs cycle involving acetyl coenzyme A?
Acetyl coenzyme A offloads the acetate.
156
acetate + oxaloacetate --> ?
acetate + oxaloacetate --> citrate
157
What happens to citrate in the krebs cycle?
Citrate is decarboxylated and dehydrogenated to form a 5 carbon compound.
158
What happens to the 5 carbon compound that is formed from the decarboxylation and dehydrogenation of citrate?
The 5 carbon compound is decarboxylated and dehydrogenated to form a 4 carbon compound
159
What happens to the 4 carbon compound that forms after the 5 carbon compound and citrate in the krebs cycle?
The 4 carbon compound is converted into another 4 carbon compound. ADP is phosphorylated to ATP.
160
What happens to the second 4 carbon compound formed in the krebs cycle?
The second 4 carbon compound is dehydrogenated to form another 4 carbon compound.
161
What happens to the third 4 carbon compound in the krebs cycle?
The third 4 carbon compound is dehydrogenated to reform oxaloacetate.
162
What is the first step in oxidative phosphorylation?
Reduced NAD & FAD are reoxidised as they donate hydrogen atoms.
163
How many hydrogen atoms are donated per reduced NAD or reduced FAD in oxidative phosphorylation?
2 hydrogen atoms are donated per reduced NAD or reduced FAD.
164
What happens to the hydrogen atoms that are donated by the reduced NAD and FAD in oxidative phosphorylation?
Hydrogen atoms are split into protons and electrons.
165
What happens to the electrons from the donated hydrogen atoms in oxidative phosphorylation?
The electrons are passed along the electron transport chain (ETC) they are then passed to an oxygen atom, the final electron acceptor.
166
What does the flow of electrons along the electron transport chain cause in oxidative posphorylation?
The flow of electrons along the electron transport chain releases energy which is used to pump protons across the intermembrane space.
167
What does the protons being pumped into the intermembrane space in oxidative phopshorylation cause?
A proton gradient to build up.
168
What happens to the protons in oxidative phosphorylation once the proton gradient is established?
Protons then diffuse down their concentration gradient through channels associated with the ATP synthase enzyme.
169
What does the proton motive force from the movement of protons down their concentration gradient cause in oxidative phosphorylation?
The proton motive force turns the ATP synthase enzyme and joins ADP & Pi to make ATP.
170
What happens to the H+ ions from the donated hydrogen at the start of oxidative phosphorylation?
The H+ ions join the oxygen and electrons to make water.
171
What is the resting potential of a membrane?
-60mV
172
What is the threshold potential of a membrane?
-50mV
173
Outline the events involved in an action potential.
* the membrane is polarised, a resting potential of -60mV
* Na+ channels open, Na+ diffuses into the cell. If the cell does not reach the threshold potential nothing will happen.
* if the membrane does slightly depolarise to reach its threshold potential of -50mV then voltage gated Na+ channels open and Na+ floods in to reach +40mV an action potential
* Na+ channels close. K+ channels open
* K+ diffuses out of the cell repolarising the membrane
* often too many K+ flood out making the membrane hyperpolarised so the original potential difference is restored
174
What is the potential difference that needs to be reached for an action potential?
+40mV
175
Outline the events in an action potential being transmitted across a synapse.
* an action potential arrives at the pre-synaptic knob
* voltage-gated calcium ion channels open & Ca2+ diffuses into the presynaptic knob
* this causes vesicles to move and fuse with the pre-synaptic membrane. The neurotransmitter acetylcholine is moved out by exocytosis.
* acetylcholine diffuses across the synaptic cleft. It binds to the receptor sites on Na+ channels on the post-synaptic membrane
* Na+ channels open, Na+ diffuses across the post-synaptic membrane into the post-synaptic neurone
* Generator potential / excitatory post-synaptic potential (EPSP) created
* if sufficient generator potentials combine and are big enough, membrane reaches threshold potential
* new action potential created in post-synaptic neurone
176
What elements make up carbohydrates?
Carbon, hydrogen and oxygen.
177
What is the general formula of monosaccharides?
(CH2O)n
n can be 3, 5 or 6
178
What are the functions of lipids?
* Energy Storage
* Making Biological Membranes
* Insulation
* Protection - e.g. protecting plant leaves from drying up
* Buoyancy
* Acting as hormones
179
What two molecules are lipids made from?
Lipids are made from glycerol and fatty acids.
180
What is the primary structure of a protein?
A protein's primary structure is the linear chain of amino acids that make up its sequence.
181
What is the secondary structure of a protein?
The secondary structure is the hydrogen bonding between different amino acids creating a three-dimensional geometry like an alpha helix or pleated sheet.
182
What is the tertiary structure of a protein?
The tertiary structure describes the overall shape of the protein. Most tertiary structures are either globular or fibrous.
183
Which proteins are usually globular?
Non-structural proteins are usually globular.
184
Which proteins are usually fibrous?
Structural proteins are usually fibrous.
185
What is the quaternary structure of a protein?
Quaternary structures describe the protein's appearance when a protein is composed of two or more polypeptide chains. Often the polypeptide chains will hydrogen bond with each other in unique patterns to create the desired protein configuration.
186
What is the main genetic material that is used in viruses?
RNA
187
What is the transition state?
When a substance is no longer a reactant but not yet a product. It is the highest energy state.
188
How do enzymes function as catalysts in terms of the transition state.
Enzymes can stablise the transition state. Their active site is shaped to fit the transition state better than the substrate.
189
What does Michaelis-Menten equation describe?
The Michaelis-Menten equation describes the velocity of enzymatic reactions (v) by relating it to [S] - concentration of a substrate S.
190
What does V0 mean in the Michaelis-Menten equation?
V0 represents the intial velocity (moles/time)
191
What does [S] mean in the Michaelis-Menten equation?
[S] represents the substrate concentration (molar).
192
What does Vmax represent in the Michaelis-Menten equation?
Vmax represents the maximum velocity in the Michaelis-Menten equation
193
What does Km represent in the Michaelis-Menten equation?
Km represents the substrate concentration at half Vmax in the Michaelis-Menten equation.
194
What does Km MEAN in the Michaelis-Menten equation?
```
Km is (roughly) an inverse measure of the affinity or strength of binding between the enzyme and its substrate.
The lower the Km, the greater the affinity (so the lower the concentration of substrate needed to achieve a given rate).
```
195
How may enzymes be saved in a reaction to be used again?
To allow their re-use, enzymes may be immobilised (attached to an inert, insoluble material such as calcium alginate to form a gel capsule around them).
This way, the enzymes will be hold in place throughout the reaction, easily separated from the products and may be used again.
196
Lineweaver-Burk plot is a reciprocal of what?
Lineweaver-Burk plot is a reciprocal of the Michaelis Menten equation.
197
How is Vmax calculated from a Lineweaver Burk plot?
Vmax is determined by the point where the line crosses the 1/Vi = 0 axis (so the [S] is infinite).
198
How is Km determined from a Lineweaver Burk plot?
Km equals Vmax times the slope of line.
| This is easily determined from the intercept on the X axis.
199
What are examples of intracellular receptors?
Nuclear receptors and cytoplasmic receptors.
200
What are typical ligands for nuclear receptors?
The typical ligands for nuclear receptors are non-polar hormones like the steroid hormones testosterone and progesterone and derivatives of vitamins A and D.
201
What is the function of nuclear receptors?
In response, these receptors work with other proteins to regulate the expression of specific genes, thereby controlling the development, homeostasis, and metabolism of the organism.
Nuclear receptors have the ability to directly bind to DNA and regulate the expression of adjacent genes, hence these receptors are classified as transcription factors.
The regulation of gene expression by nuclear receptors generally only happens when a ligand — a molecule that affects the receptor's behavior — is present.
202
What is a transcription factor?
A transcription factor is a protein that binds to specific DNA sequences, thereby controlling the rate of transcription of genetic information from DNA to messenger RNA.
203
What is homeostasis?
The maintenance of the body's internal environment.
204
What feedback mechanisms is homeostasis controlled by?
Negative feedback mechanisms control homeostasis.
205
Where in the brain is the body's temperature monitored?
In the hypothalamus.
206
In what direction is a signal transmitted along an axon/synapse?
The signal transmitted is always axon --> dendrite, unidirectional, because specific neurotransmitter receptors are only found on the dendrites!
207
What is serotonin?
Serotonin is a monoamine neurotransmitter.
208
Where is serotonin found?
Serotonin is primarily found in the gastrointestinal tract, blood platelets, and the central nervous system (CNS) of animals, including humans.
209
Where is approximately 90% of the body's serotonin found?
Approximately 90% of the human body's total serotonin is located in the enterochromaffin cells in the GI tract.
210
What is the function of the serotonin in the enterochromaffin cells of the GI tract?
It is used to regulate intestinal movement.
211
What is the function of the serotonin that is synthesised in the serotenergic neurons of the CNS?
Has various functions including the regulation of mood, appetite, and sleep.
212
Where is oxytocin synthesised and secreted from?
Oxytocin is normally produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary.
213
What is the function of oxytocin?
It plays a role in social bonding, sexual reproduction in both sexes, and during and after childbirth.
214
What is oxytocin?
Oxytocin (Oxt) is a hormone, neuropeptide, and medication.
215
What is the precursor molecule in the formation of dopamine?
L-DOPA
216
What is the function of dopamine in the brain?
The brain includes several distinct dopamine pathways, one of which plays a major role in reward-motivated behavior. Most types of reward increase the level of dopamine in the brain, and many addictive drugs increase dopamine neuronal activity. Other brain dopamine pathways are involved in motor control and in controlling the release of various hormones.
217
What is a disease that is famously affected by dopamine levels?
Parkinson's disease is caused by a loss of dopamine-secreting neurons in an area of the midbrain called the substantia nigra.
218
What does a neuromuscular junction consist of?
A neuromuscular junction has a signal travelling from a motor neurone to a muscle cell's motor end plate.
219
How many molecules of ATP can be yielded from one molecule of glucose?
38 molecules of ATP can be yielded from one molecule of glucose - this is a best case scenario. - More like 29-30 ATPs.
220
What is the main useful purpose of the Krebs cycle?
To generate plenty of NADHs and FADH2s for the electron transport chain to use for generating ATP.
221
Which stage of respiration can take place anaerobically?
Glycolysis can take place anaerobically.
222
What is the product of anaerobic respiration in yeasts?
Ethyl alcohol.
223
What is the product of anaerobic respiration in humans?
Lactic acid.
224
What is a gene?
A gene is the basic physical and functional unit of heredity. Genes, which are made up of DNA, act as instructions to make molecules called proteins.
225
What is an allele?
An allele is an alternative version of a gene.
226
What is the smallest gene?
The smallest gene is the tRNAs which are 76bp long
227
What is the longest/largest gene?
Titin is 80,781 base pairs (26,926 amino acids)
228
How many genes do humans have?
The Human Genome Project predicts humans have 20,000-25,000 genes.
229
Which organelle triggers the intrinsic mechanism of apoptosis?
The mitochondria.
230
How many genes are present in mitochondrial DNA?
37 genes.
231
What is DNA coiled around in a chromosome?
DNA is coiled around a histone protein in a chromosome.
232
What point in a chromosome divides it into two arms?
The centromere divides the chromosome into two arms.
233
What is the short arm of a chromosome labelled?
The short arm of a chromosome is the p arm.
234
What is the long arm of a chromosome labelled?
The long arm of a chromosome is the q arm.
235
What are introns?
Introns are non-coding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein.
236
What are introns also referred to as?
Introns are also referred to as intervening sequences.
237
What is the function of introns?
Introns are integral to gene expression and regulation.
238
What are exons?
Exons are coding sections of an RNA transcript, or the DNA encoding it, that are translated into protein.
239
How are adjacent ribose nucleotide bases chemically attached to one another?
Phosphodiester bonds.
240
TRUE or FALSE
| RNA is more prone to degradation than DNA?
TRUE!
| RNA contains ribose sugars rather than deoxyribose sugars, which makes RNA more unstable and more prone to degradation.
241
Which enzyme synthesises RNA during transcription?
RNA polymerase
242
What is chromatin?
Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.
243
What are the two forms of chromatin?
Euchromatin and heterochromatin.
244
Which form of chromatin is less condensed and can be transcribed?
Euchromatin
245
Which form of chromatin is highly condensed and typically cannot be transcribed?
Heterochromatin
246
What do transcription factors do?
Transcription factors can bind to specific DNA sequences called enhancer and promoter sequences in order to recruit RNA polymerase to an appropriate transcription site.
247
What is always the start codon in translation?
Methionine
248
In what three stages does translation occur?
Initiation, elongation and termination
249
To which end of an mRNA molecule is a methylated cap added?
A methylated cap is found on the 5' end of an mRNA molecule.
250
After transcription of mRNA what happens to the 3' end?
Specific nucleotide sequences in the mRNA are bound by cleavage factors
The 3' end is then moved into the correct configuration for cleavage
Stabilising factors are added to the complex
PolyA polymerase binds and cleaves the 3' end
Adds adenine residues to the 3' end
251
What is the function of the 5' cap?
The 5′ cap has four main functions:
* Regulation of nuclear export
* Prevention of degradation by exonucleases
* Promotion of translation
* Promotion of 5′ proximal intron excision
252
How many adenosine residues are found in the polyA tail?
50-250 adenosine residues
253
What is the function of mRNAs polyA tail?
Increases the stability of the mRNA molecule and prevents its degradation
254
What is a promoter sequence?
Promoter sequences are DNA sequences that define where transcription of a gene by RNA polymerase begins.
Promoter sequences define the direction of transcription and indicate which DNA strand will be transcribed.
255
What is the DNA strand that is transcribed called?
The DNA strand that is transcribed is called the sense strand.
256
What is the TATA box?
It is a type of promoter sequence, which specifies to other molecules where transcription begins.
257
Where is the TATA box found?
Many eukaryotic genes have a conserved TATA box located 25-35 base pairs before the transcription start site of a gene.
258
How many types of RNA do bacteria contain?
One
259
How many types of RNA do eukaryotic cells contain?
Three
260
What is DNA polymerase?
```
DNA polymerase (DNAP) is a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules.
DNA polymerase is responsible for the process of DNA replication, during which a double-stranded DNA molecule is copied into two identical DNA molecules.
```
261
What is splicing?
Removal of introns and connecting of exons in eukaryotic pre-mRNAs.
262
TRUE or FALSE
| Only eukaryotes have a spliceosome?
TRUE!
| Only eukaryotes have a spliceosome.
263
What are snRNPs?
snRNPs (pronounced "snurps"), or small nuclear ribonucleo proteins, are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs. The action of snRNPs is essential to the removal of introns from pre-mRNA.
264
What is alternative splicing?
Alternative splicing is a regulated process during gene expression that results in a single gene coding for multiple proteins.
In this process, particular exons of a gene may be included within or excluded from the final mRNA produced from that gene.
Consequently, the proteins translated from alternatively spliced mRNAs will contain differences in their amino acid sequence and, often, in their biological functions.
Notably, alternative splicing allows the human genome to direct the synthesis of many more proteins than would be expected from its 20,000 protein-coding genes.
265
What is a primer?
A primer is a short RNA nucleic acid sequence that provides a starting point for DNA synthesis.
266
Which enzyme synthesises primers?
Primase
267
What type of enzyme is primase?
Primase is a tye of RNA polymerase.
268
What do DNA helicases do?
DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
269
What is the function of RNA helicases?
RNA helicases are involved in shaping the form of RNA molecules, during all processes involving RNA, such as transcription, splicing, and translation.
270
What does PCR stand for (in terms of genetics)?
The polymerase chain reaction.
271
What is the purpose of PCR?
PCR is used to make multiple copies of a segment of DNA.
| PCR is very precise and can be used to amplify, or copy, a specific DNA target from a mixture of DNA molecules.
272
What is the first step in PCR?
Heat is applied to denature the strands to separate them.
273
What is the DNA polymerase used in PCR?
Taq polymerase.
Isolated from the Thermos aquaticus bacteria living in geysers in Yellowstone National Park, can withstand the high temperatures of denaturing the DNA.
274
What is added to the mixture for PCR?
Primers - so the Taq polymerase has something to bind to.
| Free nucleotides.
275
Why do we want multiple copies of a gene from PCR?
PCR is a common tool used in medical and biological research labs. It is used in the early stages of processing DNA for sequencing, for detecting the presence or absence of a gene to help identify pathogens during infection, and when generating forensic DNA profiles from tiny samples of DNA.
(basically to make lots of copies of a gene for various methods of testing).
276
What is recombinant DNA?
A type of DNA sequence that is composed of sequences from two or more different sources or organisms, such as human and pig sources, or synthetic sequences and microorganisms.
277
What is a plasmid?
A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA.
278
TRUE or FALSE
| When bacteria replicate, the daughter cells inherit their plasmids?
When a bacterium divides, all of the plasmids contained within the cell are copied such that each daughter cell receives a copy of each plasmid.
279
What is a transgene?
A gene that has been transferred from the genome of one species into that of another.
280
What charge must the gel have in electrophoresis?
The further end of the gel has a positive charge and the other end has a negative charge as DNA is negatively charged.
281
What is gene therapy?
Use of recombinant DNA to treat a disease or disorder by altering the genetic makeup of the patient's cells.
282
What is a restriction endonuclease?
A restriction enzyme, which recognizes particular base sequences in DNA and makes double-stranded cuts nearby.
283
What is conjugation?
Conjugation is the process by which one bacterium transfers genetic material to another through direct contact.
During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. The donor bacterium carries a DNA sequence called the fertility factor, or F-factor. The F-factor allows the donor to produce a thin, tubelike structure called a pilus, which the donor uses to contact the recipient.
The pilus then draws the two bacteria together, at which time the donor bacterium transfers genetic material to the recipient bacterium
Typically, the genetic material is in the form of a plasmid, or a small, circular piece of DNA.
The genetic material transferred during conjugation often provides the recipient bacterium with some sort of genetic advantage. For instance, in many cases, conjugation serves to transfer plasmids that carry antibiotic resistance genes.
284
What is transformation (in prokaryotes)?
Transformation is a process by which foreign genetic material is taken up by a cell. The process results in a stable genetic change within the transformed cell.
285
What is transduction (in prokaryotes)?
Transduction is the process by which a virus transfers genetic material from one bacterium to another.
286
How many ceclls are produced in mitosis?
In mitosis a parent cell divides once to produce two identical daughter cells.
287
What are the major purposes of mitosis?
Mitosis is for growth and to replace worn out cells.
288
What are the stages that are grouped as 'interpahse'?
G1, G2 and S
289
What pulls the sister chromatids apart in anaphase?
The mitotic spindle pulls sister chromatids to opposite poles.
290
What is cytokinesis?
Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells.
291
Are the cells produced by mitosis haploid or diploid?
The cells produced by mitosis are diploid.
292
What happens in the G1 step of interphase?
In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis
293
What happens in the S step of interphase?
It is the part of the cell cycle in which DNA is replicated.
294
What happens in the G2 step of interphase?
G2 phase is a period of rapid cell growth and protein synthesis during which the cell readies itself for mitosis.
295
What is the genotype of an organism?
It describes an organism's complete set of genes.
296
Define the phenotype of an organism.
The term "phenotype" refers to the observable physical properties of an organism; these include the organism's appearance, development, and behaviour.
297
Define dominant (in terms of genetics)
Refers to a trait that appears more frequently than another trait, resulting from interactions between gene alleles.
298
Define recessive (in terms of genetics)
Refers to a trait that is expressed only when genotype is homozygous; a trait that tends to be masked by other inherited traits, yet persists in a population among heterozygous genotypes.
299
What is a haplotype?
A haplotype is a group of genes within an organism that was inherited together from a single parent.
A haplotype can describe a pair of genes inherited together from one parent on one chromosome, or it can describe all of the genes on a chromosome that were inherited together from a single parent.
300
What is a dihybrid cross?
The crossing of two organisms which are both heterozygous for two traits.
A dihybrid organism is one that is heterozygous at two different genetic loci.
301
What was the ratio of alleles in Mendel's F2 generation?
9:3:3:1
302
How many cells are produced for each parent cell in meiosis?
One parent cell produces four daughter cells.
303
Are the cells produced in meiosis haploid or diploid?
Haploid
304
What are pairs of similar chromosomes called?
Homologous chromosomes
305
In what types of populations are the effects of genetic drift 'felt' more.
In smaller populations, where rare alleles have a much greater chance of being lost.
306
What is the Hardy-Weinberg equilibrium?
The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
307
What is the Hardy-Weinberg equation?
p2 + 2pq + q2 = 1
where p is the frequency of the "A" allele
and q is the frequency of the "a" allele in the population.
In the equation, p2 represents the frequency of the homozygous genotype AA,
q2 represents the frequency of the homozygous genotype aa,
and 2pq represents the frequency of the heterozygous genotype Aa.
The sum of the allele frequencies for all the alleles at the locus must be 1, so p + q = 1
308
What is gene flow?
The movement of alleles between previously separate populations caused by migration and subsequent mating.
309
What is penetrance (in terms of genetics)?
Penetrance measures the proportion of individuals in a population who carry a specific gene and express the related trait. Therefore, penetrance is a measurement of the relationship between a genotype and phenotype.
310
Define a species.
A species is a group of organisms that can reproduce with one another to produce fertile offspring and is reproductively isolated from other organisms.
311
In which stage of meiosis does recombination occur?
Prophase I
312
What is an SNP?
A single nucleotide polymorphism, or SNP (pronounced "snip"), is a variation at a single position in a DNA sequence among individuals.
If more than 1% of a population does not carry the same nucleotide at a specific position in the DNA sequence, then this variation can be classified as a SNP.
313
What is codominance?
A condition in which the alleles of a gene pair in a heterozygote are fully expressed thereby resulting in offspring with a phenotype that is neither dominant nor recessive. (red and white flower cross resulting in flowers with red and white spotted petals)
314
What is a common genetic example of codominance?
The ABO blood group system.
315
What is incomplete dominance?
When the phenotype of the offspring is a blending of both the parental phenotypes (red and white flower cross resulting in pink flowers).
316
What are polygenic traits?
Polygenic traits are controlled by two or more than two genes (usually by many different genes) at different loci on different chromosomes. These genes are described as polygenes.
Examples of human polygenic inheritance are height, skin colour and weight. Polygenes allow a wide range of physical traits. For instance, height is regulated by several genes so that there will be a wide range of heights in a population.
317
What is pleiotropy?
The production by a single gene of two or more apparently unrelated effects.
318
What is an autosome?
An autosome is a non-sex chromosome.
319
What are bundles of neurons called?
Bundles of neurons are called nerves.
320
What is in the central nervous system?
The central nervous system consists of brain and spinal cord.
321
What is in the peripheral nervous system?
Motor and sensory neurons that gather information to send to the CNS. Then when the CNS makes a decision about the action that should be taken, the PNS does it.
322
Where do afferent neurons carry signals?
Afferent neurons carry signals to the brain and spinal cord. (sensory neurons)
323
Where do efferent neurons carry signals?
Efferent neurons carry information out of the central nervous system. (motor neurons)
324
What are the two different sections of the peripheral nervous system called?
* the somatic system
| * the autonomic system
325
What does the somatic nervous system control?
The somatic nervous system controls all the stuff you THINK about doing
326
What does the autonomic nervous sytem do?
The autonomic nervous system controls all the stuff your body does without thinking about them. (heartbeat, digestion, breathing, ouch thats too hot, etc).
327
What are the two branches of the autonomic nervous system?
* sympathetic
| * parasympathetic
328
What does the sympathetic nervous system do?
Sympathetic nervous system is responsible for the fight or flight response.
329
What does the parasympathetic nervous system do?
The parasympathetic nervous system calms down responses (lowers heart rate etc).
330
Where do dendrites receive information from?
Dendrites receive information from other neurons.
331
What is the type of conduction that occurs because the siignal jumps between nodes of Ranvier called?
Saltatory conduction
332
What is the currency of the sodium potassium pump?
For every 3 Na+ ions it lets out, 2 K+ ions come in
333
Which cells types make up about half the mass of the brain outnumbering neurons 10 to 1?
Glial cells.
334
What is the function of the glial cells? (nervous system)
Glial cells are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems.
335
What is the function of atrocytes? (nervous system)
Anchor neurons to their blood supply and govern exchange of materials between neurons and capillaries.
336
What is the function of microglial cells? (nervous system)
Microglial cells are the main source of immune defencse against invading microorganisms in the brain and spinal cord.
337
What is the function of ependymal cells? (nervous system)
Creates and secretes cerebrospinal fluid that fills cavities and cushions organs.
338
What is the function of oligodendrocytes? (nervous sytem)
Wrap around neurons producing an insulating barrier called the myelin sheath.
339
What is the cell body of neurons also referred to as?
The cell body of neurons is also referred to as the soma.
340
Where might you find a bipolar neuron?
Bipolar neurons are pretty rare. Can be found in the retina of your eye.
341
Where might you find unipolar neurons?
Unipolar neurons are found in sensory receptors.
342
What is peristalsis?
Peristalsis is a series of wave-like muscle contractions that moves food to different processing stations in the digestive tract. The process of peristalsis begins in the esophagus when a bolus of food is swallowed.
343
Why does the stomach contain mucus?
The stomach has mucus to protect itself from the hydrochloric acid and pepsin so it doesn't start digesting itself, otherwise you get peptic ulcers.
344
What is the main function of the stomach?
To break down the bolus of food into chyme.
345
What is the main function of the small intestine?
To absorb the nutrients from the food via the mcrovilli on the villi.
346
What is the main function of the large intestine?
To reabsorb water from the food.
347
What are the three sections of the small intestine called?
* duodenum
* jejunum
* ileum
348
What is the function of the duodenum?
The duodenum is largely responsible for the breakdown of food in the small intestine, using enzymes. Brunner's glands, which secrete mucus, are found in the duodenum only.
349
What is the function of the jejunum?
The lining of the jejunum is specialized for the absorption, by enterocytes, of small nutrient particles which have been previously digested by enzymes in the duodenum.
350
What is the function of the ileum?
The function of the ileum is mainly to absorb vitamin B12 and bile salts and whatever products of digestion were not absorbed by the jejunum. The wall itself is made up of folds, each of which has many tiny finger-like projections known as villi on its surface. In turn, the epithelial cells that line these villi possess even larger numbers of microvilli. Therefore, the ileum has an extremely large surface area both for the adsorption (attachment) of enzyme molecules and for the absorption of products of digestion.
351
What are the three types of salivary glands?
* parotid glands
* sublingual glands
* submandibular glands
352
What is the purpose of bile?
Bile aids digestion of fats by acting as an emulsifier and stopping them glooping together so lipase enzymes can break them down into fatty acids and glycerides which are much easier to digest.
353
What does nuclease do?
Breaks down DNA and RNA n food into nucleotides.
354
What is the artery that gives blood to the intestines?
The mesenteric artery gives blood to the intestines.
355
What is the blood supply from the intestines to the liver called?
The hepatic portal vein connects the intestines to the liver.
356
Does more of the livers blood supply come from the hepatic artery or the hepatic portal vein?
The liver obtains about 75% of its blood supply from the hepatic portal vein and only around 25% from the heptaic artery.
357
What are the specialist liver macrophages called?
Kupffer cells.
358
What do catabolic reactions do?
Catabolic reactions break stuff down and release energy.
359
What do anabolic reactions do?
Anabolic reactions assemble stuff together and consume energy.
360
What does vitamin C do?
Vitamin C helps iron absorption.
361
What does vitamin K do?
Vitamin K is crucial to blood clotting.
362
What do B vitamins do?
Some B vitamns are important in the production of ATP from glucose.
363
What do calcium, magnesium and phosphorus do?
Harden bones and teeth.
364
What is iron used for?
Iron is a crucial part of haemoglobin.
365
What do potassium, sodium and chlorine do?
Help maintain bodys pH balance and are used in action potentials.
366
Which fatty acids are termed essential fatty acids and why?
Omegas 3 and 6 are called essential fatty acids because the body can't make them.
367
How many amino acids are there that are 'essential' and have to be eaten?
Nine
368
What are insect exoskeletons made of?
Chitin
369
Which cell types 'build bones'?
Osteoblasts
370
Which cells break bone down?
Osteoclasts
371
What is building bones called?
Ossification
372
What does vitamin D do?
Help the absorption of calcium through the small intestine.
373
What do tendons do?
Tendons connect muscle to bone.
374
What are tendons made of?
Collagen
375
What do ligaments do?
Ligaments connect bones to other bones.
376
What are muscle cells called?
Myofibrils
377
What is a bundle of myofibrils called?
Fascicle
378
Why are muscle cells multinucleate?
Muscle cells are multinucleate because they are essentially big strands of protein. To make protein you need nuclei.
379
What is a sarcomere?
A structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band.
The contractile unit of a skeletal muscle fiber.
