topic eleven Flashcards
(182 cards)
1
Q
antigen define
A
any moelcule that can trigger an immune response leading to the generation of antibodies
2
Q
all red blood cells have antigen ___ ontheir surface
A
H
3
Q
what is added to antigen H for blood group a
A
For blood group A, N-acetylgalactosamine is added,
4
Q
what is added to antigen H for blood group b
A
galactose is added
5
Q
The immune system forms antibodies against whichever ABO blood group antigens are ??? found on the individual’s RBCs
A
not
6
Q
what is agglutination
A
hemolysis and potentially death
7
Q
The transfusion of type A blood to a person who has type O blood would result in:
A
The recipient’s anti-A antibodies clumping the donated red blood cells
8
Q
how does the body deal with an infection
A
- The antigen is quickly ingested (via phagocytosis) by macrophages and B cells. Both process the antigen and present it on their surface.
- The macrophage (now called antigen-presenting cell) interacts with a helper T cell. This activates the helper T cell.
- The activated helper T cell interacts with the B cell that has the antigen on its surface (shown in step 2 in the diagram) and activates it. The activated B cell rapidly divides by mitosis to form clones of plasma cells and memory cells. The plasma cells possess lots of rough endoplasmic reticulum and a well-developed Golgi apparatus making them well-suited for producing antibodies (of one specific type) against the antigen.
- The memory B cells, produced in much smaller amounts than the plasma cells, stay in the body for years after both plasma cells and antibodies have disappeared. If an infection with the same antigen recurs, the memory B cells quickly divide to form plasma cells (as well as a new set of memory cells), which secrete antibodies against this specific infection. Memory cells provide long-term immunity to diseases.
9
Q
diagram of an antibody
A
10
Q
what is the variable tregion of an antibody
A
highly specific to a particualar antigen
11
Q
how can pathogens be inactivated
A
neutralisation
agglutination
complement
12
Q
what is neutralisation inactivation of pathogens
A
binds to pathogen to block key biological activity eg inhibits virus entry into host cells
13
Q
agglutination inactivation of pathogens
A
causes clumping of pathogens so phagocytes can engluf a number of pathogens at once
14
Q
opsonisation
A
Opsonisation is the coating of a pathogen with antibodies to promote and enhance phagocytosis.
15
Q
what are complement proteins
A
a group of more than 20 proteins that are present in blood and tissue fluid. These are normally in an inactive form. Some of the complement proteins become activated when they are presented with antigens.
16
Q
When an antigen bound to an antibody is presented to a complement protein,
A
the complement is activated and binds to the pathogen. this then causes the pathogens to lyse or encourages phagocytosis
17
Q
antigens are anything that
A
triggers an immune repsonse
18
Q
antibodies are produced by
A
plasma cells (originally B cells)
19
Q
what is the primary response
A
The immune response triggered on the first encounter of the body with an antigen
20
Q
waht is produced following the primary response
A
memory cells are so that if there is another infection with the same patogen, your body can react quickly
21
Q
vaccinations
A
inject an attenuated (weakened) form of the pathogen, or a toxin that is produced by the pathogen, into the body. Vaccines contain antigens that trigger immunity but do not cause the disease.
22
Q
what causes smallpox
A
Variola major and V. minor
23
Q
what is zoonoisis
A
where pathogens can cross the species barrier eg ebola in monkeys eventually also in humans
24
Q
epidemiology
A
the study of the distribution, patterns and causes of diseases in a population. By studying the spread, patterns and causes of diseases, predictions can be made and preventative measures undertaken.
25
allergen
the study of the distribution, patterns and causes of diseases in a population. By studying the spread, patterns and causes of diseases, predictions can be made and preventative measures undertaken.
26
what produces hitamine
basophils and mast cells (both are types of white blood cells) found in the connective tissues
27
one of the functions of histamine is to
dilate and increasae the permeability of capillaries. this enables wbc such as mast cells and some proteins to invade the affected tissues and engage the allergens
28
Immune response after an allergen has entered the body.
29
uses of monocolonal antibodies
cancer tests
preganancy tests
They are also used as therapeutic agents in rheumatoid arthritis, B cell leukaemia and non-Hodgkin's lymphoma. Georges Köhler, César Milstein and Niels Kaj Jerne published this technique in 1975 and shared the Nobel Prize in Physiology or Medicine in 1984 for the discovery.
30
eptitope
a short amino acid sequence on the antigen that the antibody is able to recognise.
31
what cells are fused to make a hybridoma
tumour and antibody producing plasma cell
32
what cell makes monocolonal antibodies
hybridoma cells
33
how are monocolonal antibodies produced
A mouse is injected with an antigen X (1) for which a monoclonal antibody is needed. Once the mouse's spleen starts to produce polyclonal antibodies in its plasma B cells, the spleen is removed (3) and is fused with myeloma cells (an immortalised, cancerous cell line; these myeloma cells have lost certain abilities, such as the ability to replicate their own DNA). Cells are cultured on a medium that is selective for fused (hybridoma) cells (4). Unfused myeloma cells cannot grow because they cannot replicate their DNA (2). The hybridoma cells can replicate their own DNA (5). Each hybridoma cell is then cultured separately and screened. Once it is confirmed that a certain hybridoma is producing the right antibody, it is cultured indefinitely and monoclonal antibodies are harvested from it.
34
how do preganancy tests work
detects presence of HCG
(a) The test stick is dipped into the woman’s urine.
(b) The test stick contains anti-HCG antibodies with attached blue dye. If HCG is present it will bind to the antibodies.
(c) Monoclonal antibodies are attached to the membrane within a window on the test stick. If HCG is present in the urine and bound to the anti-HCG antibodies, the HCG will also bind to the monoclonal antibodies as it travels up the stick. This complex also contains the blue dye which shows a blue line within the window. This blue line indicates the presence of HCG and therefore a positive result.
(d) The urine continues to move up the test stick. As it reaches the top there is another line of monoclonal antibodies. These antibodies are a complementary shape to the anti-HCG. The anti-HCG is always present therefore this line will always turn blue as a result of the blue dye. This line acts as a control and allows the user to check if the test is working. This line does not indicate whether the user is pregnant or not.
35
Monoclonal antibodies are produced by fusion between:
Mouse spleen B cells and myeloma cells
36
where are muscles attached in insects
to the exoskeleton
37
what is the exoskeleton
an external structure usually made of chitin (a modified polysaccharide containing nitrogen) that protects the softer body parts of these animals
38
antagonistic meaning
when one muscle contracts, the other relaxes
39
Hind limb of a cockroach diagram
40
What is the role of bones and the exoskeleton in organisms?
To provide anchorage for muscles and act as levers
41
what is bone amde of
many material sincludign calcium phosphate, collagen and elastic protein
42
what are synovial joints
joints that possess a synovial cavity between the two bones. This cavity is filled with synovial fluid that reduces friction at the joint, allowing bones to move freely. Synovial joints allow a high range of motion. However, synovial joints allow certain movement but not others.
43
what is a dislocation
an injury to a joint where the bone ends are forced from their normal positions
44
labelled knee joint
45
labelled hip joint
46
labelled elbow joint
47
what should joint annotations conatain
Annotations should include cartilage, synovial fluid, joint capsule, named bones and named antagonistic muscles.
48
what type of joint is th ehip
It is a ball and socket joint that can flex and extend in many directions.
49
The cell membrane of a striated muscle fibre cell is known as
the sarcolemma
50
Muscle fibres consist of many myofibrils and have a lot of endoplasmic reticula; however, in muscles, this is called
the sarcoplasmic reticulum
51
waht does the sarcoplasmic reticulim store
calcium
52
labelled sarcomere
53
sarcomeres are found in
skeletal and cardiac muscles
54
sliding filament theory
the actin and myosin filaments slide over each other to make the muscle shorter: actin slides over myosin moving inwards towards the centre of the sarcomere. This makes the length of all the sarcomeres shorten, thus the entire muscle becomes shorter.
55
steps in sarcomere contraction
ATP attaches to myosin head.
Myosin head detaches from its binding site on actin filament.
ATP splits into ADP and P.
Myosin head cocks to an angle.
Myosin head attaches to binding site on actin filament.
As ADP and P detach, the myosin head changes position and pushes the actin filament along – this is known as the power stroke.
The myosin head detaches from the actin filament and reattaches to the next binding site, repeating the cycle. This achieves 'movement'.
56
When a muscle receives a neuronal impulse to contract, the following happens:
Calcium ions are released from the sarcoplasmic reticulum.
Calcium ions bind to troponin, which forces tropomyosin to move.
This move exposes the myosin-binding sites on the actin.
Myosin heads can now make a cross bridge and pivoting the actin filaments towards the centre of the sarcomere.
57
animals excrete their nitrogenpus waste in three mainf orms:
urea, uric acid and ammonia
58
osooregualtors
organisms that are able to keep or regulate the solute concentration of their body fluids above or below that of their external environment. These organisms have the ability to control the osmolarity of their tissues within very narrow limits. Changes in their environment generally have no effect on or cause only small fluctuations in their internal solute concentration. Examples of osmoregulators include humans and birds.
59
osmoconfromers
Osmoconformers are marine organisms that actively or passively maintain an internal environment that is isosmotic to their external environment. This means that the solute concentration of their body fluid is the same as the solute concentration of the external medium in which the organisms live. These organisms cannot regulate the solutes of their body fluids at a concentration that is different from that of the external medium. Examples of osmoconformers include sea stars, molluscs, marine crabs, jellyfish and other marine invertebrates.
60
what can happen if someone is overhydrated
The consequence of overhydration is the swelling of body cells. This creates a very dangerous situation, as swollen cells in the brain lead to intracranial pressure. As this pressure increases, the blood flow to the brain can be interrupted, leading to dysfunction in the central nervous system, seizures, coma or even death. Additionally, consequences such as nausea and vomiting, changes in mental state (confusion or disorientation), muscle weakness or cramps, as well as unconsciousness may occur.
61
what is osmoregualtion
the maintenance by an organism of an internal balance between water and dissolved materials, regardless of environmental conditions. It includes the control of the water balance of the blood, tissue or cytoplasm of a living organism.
62
labelled kidney
63
why is glucose reabsobred
for metabolic proccesses
64
where is the carbon dioxide higheer, renal artery or renal vein
renal artery
65
You should be able to annotate the following parts on nephron diagrams:
glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule and the collecting duct.
66
bowmans capsule function
Highly porous wall which collects the filtrate
67
glomerulus function
Knot-like capillary bed where high-pressure filtration takes place
68
pct function
Twisted section of the nephron where water, nutrients and salts are reabsorbed back into the blood; contains many mitochondria and microvilli
69
loop of henle function
Hairpin shaped tube with a descending and ascending limb; water and salt reabsorption takes place here
70
dct function
Another twisted section of the nephron, where water and salts are reabsorbed back into the blood; also contains many mitochondria and microvilli
71
collecting duct
A slightly wider tube that carries the filtrate to the renal pelvis
72
afferent ateriole function
Brings blood from the renal artery
73
efferent ateriole function
A narrow blood vessel that restricts blood flow, which helps to generate the pressure needed for filtration
74
vasa recta function
An unbranched capillary shaped like the loop of Henle, with the descending limb bringing blood deep into the medulla
75
labelled bowmans capsule
76
what do podocytes do
support the capillaries and regulate the filtration process
77
labelled podocyte
78
what is the basement membarne composed of
glycoproteins
79
where does ultrafiltration ocur
the basement membrane in the capillaries in the glomerulus
80
what do fenestrations in the capillary wall allow
blood to flow out and it acts like a sieve to stop the blood cells and large proteins . Thus, white and red blood cells cannot pass through, but small proteins, salts and nutrients can.
81
where does the unusuually high cap pressure come from
the result of the short, large diamter afferent aterioles conveying blood at high arterial pressure directly to the glomerular capillaries. The smaller diameter of the efferent arterioles leaving the glomerulus also helps maintain the pressure by restricting the outflow of blood.
82
Out of all the dissolved substances present in the filtrate, only useful substances are reabsorbed by active transport.
Cells of the proximal convoluted tubule have large numbers of WHAT to provide energy for active transport.
mitochondria
83
84
main function of the nephron
to reabsorb all the importatnt salts an nutrients (such as glucose) that have been filtered out of the plasma.
85
Proximal convoluted tubule and the reabsorption process.
86
PCT reabsorption process
1. The pumps use ATP for active transport to shuttle Na + (out of the tubule) and K + (into the tubule). As a result of this the Cl - are attracted to the space outside the tubule because of the positively charged Na + .
2. Glucose and amino acids are absorbed along with Na + from the filtrate by specific carrier proteins down their concentration gradient. Since absorption of glucose and amino acids into the proximal convoluted tubule is powered by active transport of Na + into blood, it is referred to as secondary active transport.
3. The glucose and amino acid concentration within the proximal convoluted tubule cells increases as they are absorbed from the filtrate. This concentration is higher than that of blood plasma, thus both glucose and amino acids are reabsorbed into blood by diffusion. Microvilli in the tubule wall cells greatly increase the surface area, which in turn enhances the diffusion process.
87
why is reabsorption of glucose and amino acids into the proximal convoluted tubule classed as secondary active transport
it is reabsorbed powered by the active transport of Na+
88
waht system does the loop of henle use to achieve max reabsorption fo water and sodium ions
countercurrent.
In the descending limb of the loop of Henle, water moves out into the medullary interstitial fluid by osmosis before being reabsorbed into the vasa recta. But, because this descending loop is impermeable to sodium ions, the osmolarity of the filtrate increases as water is lost
89
what is vasa recta
Blood capillaries that run parallel to the loop of Henle
90
what is the ascending limb impermeable and permeable to
impermeable to water but permeable to Na +
Na + moves out of the filtrate into the interstitial fluid of the medulla. The salt remains near the loop of Henle (it is not immediately removed by the blood) and helps to maintain a concentration gradient in the medulla. The ultimate absorption of Na + from the interstitial fluid into the vasa recta occurs by active transport. The fluid which leaves the loop of Henle is less concentrated than the tissue fluid around it.
91
why do some animals in the desert have longer loops of nele
allows for more water reabsorption. A consequence of this adaptation is that the medulla in the kidneys of those animals, for example, a gerbil, is much thicker to accommodate the longer loop of Henle.
92
The loop of Henle is lined with epithelial cells. Which of the following statements is true of these epithelial cells?
The epithelial cells of the ascending limb have plasma membranes that are impermeable to water.
93
what secretes ADH
pituitary gland
94
what monitors the solute concentration
Osmoreceptors in the hypothalamus
95
what is ADH sometimes referred to
vasopressin
96
If the solute concentration is too high (i.e not enough water), the pituitary
secretes ADH
which travels through the bloodstream to the collecting ducts and the distal convoluted tubule. ADH increases the permeability of these structures to water, therefore more water can be reabsorbed and the solute concentration will decrease.
97
how does ADH increase permeability to water
by acting on receptors in the membrane of cells in the collecting tubules
98
aquaporins
membrane proteins. They initiate a series of events which causes vesicles with aquaporins to fuse with the surface membrane. The aquaporin then allows water molecules to pass through
99
what happens when osmolarity is back to normal
ADH secretion stops and the water channels are removed from the membrane and reform as vesicles. The collecting duct is then impermeable to water and the filtrate flowing through it is lost as urine without further water absorption.
100
primary causes of kidney failure
Diabetes and hypertension (high blood pressure) are primary causes of kidney failure, but untreated urinary tract infections can also lead to kidney problems
101
Once the kidney stops functioning or has a very limited capacity for cleansing the blood, two options are available:
kidney dialysis (also called hemodialysis) or a kidney transplant.
102
what is hemodialysis
a process that uses an artificial membrane known as dialysis tubing (found within the dialyser) to remove wastes, such as urea, from the blood as well as to restore the proper balance of electrolytes in the blood and eliminate extra fluid from the body. The dialyser is made up of two parts, one for your blood and one for a washing fluid called dialysate. The dialysis tube is a thin membrane that separates these two parts. During hemodialysis, blood cells, protein and other important molecules remain in your blood because they are too big to pass through the membrane. Smaller waste products in the blood, such as urea, creatinine, potassium and extra fluid, pass through the membrane and are washed away in the dialysate.
103
issue with kidney transplants
must find suitable doner
expensive
patient must take immunosuppressants for the rest of their lives
104
what test is used when testing urine
kits using monoclonal antibody techniques
105
what is the malpighian tubule system
in insects carries out osmoregulation and removal of nitrogenous wastes.
106
what reabsorbs most of the water na mineral salts in the malpighian tube system
thehind gut
107
insectes covnert ammonia into waht
uric acid, which is insoluble in water, and excreted as a semisolid in their faeces. The formation of uric acid instead of urea is a successful adaptation to water conservation in a terrestrial environment because less water is lost during its excretion.
108
what is gametogenesis
the process by which cells of the germinal epithelium undergo cell division and differentiation to form haploid gametes.
109
where does spermatogenesis take place
testes
110
testes are composed of
seminiferous tubules with interstitial cells (leydigP filling up the gaps in between)
111
The outer layer of the seminiferous tubule is made up of a layer of cells called
the germinal epithelium.
112
The stem cells of the germinal epithelium, also known as
spermatogonia (diploid cells)
113
how do spermatogonia develop into sperm
Spermatogonia grow into larger cells called primary spermatocytes (2n). Each primary spermatocyte carries out the first division of meiosis to produce two secondary spermatocytes (n).
Secondary spermatocytes carry out the second division of meiosis to produce two spermatids (n).
Spermatids become associated with nurse cells, called Sertoli cells, which help the spermatids to develop into spermatozoa (n) or sperm. This is an example of cell differentiation. Sertoli cells provide nurture and support. The function of Sertoli cells is to nourish the developing sperm cells through the stages of spermatogenesis.
Sperm detach from Sertoli cells and are eventually carried out of the testis by the fluid in the centre of the seminiferous tubule.
114
the process of oogenesis
At puberty, FSH (follicle stimulating hormone) begins to be produced and causes some follicles to develop each month. This allows the oocyte to complete the first meiotic division.
The first meiotic division forms two cells. The smaller of the two cells is the polar body which eventually degenerates. The larger cell becomes a secondary oocyte which enters meiosis II. Meiosis II is halted at metaphase II if fertilisation does not occur.
If fertilisation does occur, meiosis II continues and a second polar body and a ovum are produced.
115
differences in sperm and oo genesis
One important difference is that sperm cells have almost no cytoplasm, while egg cells have increased cytoplasm.
In oogenesis, the first meiotic division results in a secondary oocyte and a (first) polar body. This polar body degenerates. When the egg cell is fertilised, the second meiotic division is completed, also producing a large cell (the female gamete or ovum) and a (second) polar body, which also degenerates. Therefore, only one egg is produced per oogonium.
Mature spermatozoa (usually called sperm) have undergone a complete meiotic division, which yielded four sperm cells per spermatogonium. Sperm cytoplasm becomes reduced with every division. The result is a small cell body, which contains the genetic material, some enzymes and proteins to enable the sperm to penetrate the egg and a long tail (flagellum) to propel it forward.
Another difference is that, in humans, usually only one egg cell matures and is released during every menstrual cycle, whereas millions of sperm are produced daily.
116
What is the role of testosterone in spermatogenesis?
It stimulates the meiotic divisions of spermatogonia into spermatozoa.
117
labelled spermatogenesis
118
labelled oogenesis
119
labelled sperm
120
labelled egg
121
what do sperm follow after copulation
It is believed that the sperm follow a concentration gradient of chemicals secreted by the oocyte
122
where does fertilisation take place
fallopian tube
123
If more than one sperm could fertilise an egg, it would result in
polyploid offspring, which is normally not desirable (this is called polyspermy). There are mechanisms in place to prevent that from happening.
124
the five steps of fertilisation
A sperm cell penetrates the follicle cells and binds to the receptors of the zona pellucida.
The acrosomal reaction occurs: hydrolytic enzymes are released from the acrosome (a huge modified lysosome) by exocytosis. These enzymes make a hole in the zona pellucida allowing the sperm to make its way to the plasma membrane of the egg.
There is contact between the sperm and egg, with the fusion of the sperm and egg plasma membranes.
The sperm nucleus enters the egg cytoplasm. This triggers a number of metabolic and physical changes in the egg, that are collectively called egg activation. The main effects are the completion of the second meiotic division and a rise in the intracellular concentration of calcium (a step that prepares for the cortical reaction).
The cortical reaction hardens the zona pellucida, preventing polyspermy. This reaction involves the release of a mixture of enzymes, including several proteases, from cortical granules by exocytosis. These enzymes diffuse into the zona pellucida and alter its structure by inducing hardening of the layer, as well as the destruction of sperm receptors. As a result, additional sperm cannot bind to the zona pellucida or digest it to reach the oocyte.
125
acrosomal reaction
hydrolytic enzymes are released from the acrosome (a huge modified lysosome) by exocytosis. These enzymes make a hole in the zona pellucida allowing the sperm to make its way to the plasma membrane of the egg.
126
cortical reaction
hardens the zona pellucida, preventing polyspermy. This reaction involves the release of a mixture of enzymes, including several proteases, from cortical granules by exocytosis. These enzymes diffuse into the zona pellucida and alter its structure by inducing hardening of the layer, as well as the destruction of sperm receptors. As a result, additional sperm cannot bind to the zona pellucida or digest it to reach the oocyte.
127
When you describe the fertilisation process, ensure that you have mentioned:
The acrosome reaction.
The fusion of the plasma membrane of the egg and sperm.
The cortical reaction.
128
external fertilisation
a method of fertilisation in which two haploid gametes, a sperm and an egg cell, fuse together outside of the parents' body
129
internal fertilisation
involves the transfer of sperm into the female's body for fertilisation to occur.
130
wehn does ext fert work the best
when vast quantities of eggs and sperm are produced to increase the chances of fertilisation. This is needed because the eggs and sperm can be predated upon by other animals. Other environmental factors, such as temperature or pH, may also influence the success rates of fertilisation. Courtship rituals make sure that the male and female sex cells are released within a short distance of each other, but even so, the chances of fertilisation are very low.
131
when does in fert work best
as sperm need fluid in which to swim to the egg. In this case, the chances of fertilisation are much greater since the sex cells are closer together when released. This internal approach involves fewer eggs and sperm, but the proximity between the two increases the success rate.
132
What is the role of the acrosome in sperm?
It contains enzymes to facilitate penetration of the egg.
133
whre does the acrosome raction happen
fallopian tubes
134
where does the cortical reaction happen
fallopian tubes
135
when does the ovum divide by mitosis
after fertilisation
136
when there are 125 cells, it is called a
blastocyst
137
blastocyst diagram
138
when does the zona pellucida break down
The next stage in pregnancy is the implantation of the blastocyst in the endometrium (lining) of the uterus. The egg cell contains reserves needed for the early embryo to grow. Once these are used up the zona pellucida breaks down and allows the blastocyst to implant into the uterine wall. Finger like projections grow into the uterine wall and will develop into the placenta, allowing the embryo to access external supplies of the required nutrients.
139
why is the endometrium not shed in pregnancy
continued production of progesterone nad estrogen
140
Early in pregnancy, the embryo (more specifically the outermost layer of cells that will develop into the placenta) starts to produce
human chorionic gonadotropin (hCG)
141
what does hcg do
stimulates the corpus luteum to continue the production of progesterone and estrogen, hormones which are essential for the maintenance of the endometrium. Actually, hCG ensures that the corpus luteum remains until the placenta is fully established and can take over the role of progesterone and estrogen secretion.
142
Where does fertilisation generally take place?
Oviduct (Fallopian tube)
143
Following fertilisation, how does the zygote develop into a blastocyst?
Through mitotic division
144
what order are echidna and platypys
monotremata
145
what are the fingerlike projections called
chorionic villi
146
human placenta labelled
147
placenta functions
Exchange of material to keep the fetus alive during pregnancy (see Table 1 ).
Production of progesterone and estrogen. At the beginning of the pregnancy, this task is performed by the corpus luteum. However, the activity of the corpus luteum progressively decreases from the beginning of the eighth week. Its role is entirely replaced by the placenta at the end of the first trimester (about 12 weeks).
148
what does the short diffusion distance between maternal blood pool sand fetal blood capillaries allow for
better diffusion between the maternal and fetal blood
149
What does the fetal vein carry?
Oxygenated fetal blood away from the placenta
150
Which hormones are secreted by the placenta?
Estrogen and progesterone
151
The umbilical arteries carry blood from the fetus to the placenta and the umbilical vein carries blood from the placenta to the fetus. How does the composition of the blood in the umbilical artery and the umbilical vein differ?
Blood in the umbilical arteries contains less glucose than blood in the umbilical vein.
152
above a certain mass, there is a linear relationship between the average mass and the
gestation period
153
which hormones induce pain
The fetus signals to the placenta to stop producing progesterone. This triggers the secretion of oxytocin, which is produced by the posterior lobe of the pituitary gland and by the fetus. While the progesterone level drops prior to birth, the estrogen level continues to rise and induces the development of oxytocin receptors on the muscles of the uterine wall. This increases the responsiveness of the uterus to oxytocin.
154
how does the cervix open
pressure ffrom babies head
155
hormones after birth
After the baby is born, prolactin , a hormone produced by the anterior pituitary gland, stimulates milk production (also called lactation).
After birth, prolactin production is stimulated when the baby suckles
156
what is estrogen pollution
increased levels of these synthetic hormones in the environment. can lead to lowering perm count
157
what does AUG carry
methionine
158
When a tRNA recognises and binds to its corresponding codon of mRNA in the ribosome, the tRNA
transfers the appropriate amino acid to the end of the growing polypeptide. The ribosome acts as an enzyme to catalyse this reaction.
159
structure of trna
160
The triplet of bases at the amino acid binding site of tRNA is:
5' CCA 3'
161
How many permanent loops does a tRNA molecule have?
tRNA has three permanent loops: these are formed by the single stranded molecule folding back on itself and forming double stranded regions with loops at one end.
162
Which sentence describes the subunits of eukaryotic ribosomes?
A small subunit (which binds mRNA) and a large subunit (which binds the growing polypeptide).
A small subunit (which binds mRNA) and a large subunit )with three tRNA binding sites).
, Correct answer
Your answer
A small subunit (which binds tRNA) and a large subunit )with three mRNA binding sites).
A small subunit (containing three tRNA binding sites) and a large subunit (that binds mRNA).
A small subunit (which binds mRNA) and a large subunit )with three tRNA binding sites).
163
what does amino acyl trna synthase
Each enzyme is highly specific for an amino acid and the corresponding tRNA molecule that has the matching anticodon. This specificity is based on a match between the shape of the anticodon of the tRNA and the enzyme, as well as the match between the shape of the particular amino acid and the enzyme, thus illustrating the concept of enzyme–substrate specificity
164
Aminoacylation of a tRNA molecule.
165
tRNA with attached amino acid.
166
Once the tRNA has attached an amino acid, it is called a
charged tRNA molecule
167
when does translation begin
as soon as the mrna attaches itself to the ribosome
168
what does the srp do
The beginning of the polypeptide contains the signal sequence, which is recognised by a signal-recognition particle (SRP). The SRP then binds to the SRP receptor protein on the endoplasmic reticulum. This allows the polypeptide to enter the rough endoplasmic reticulum (RER) as it grows in length.
169
Proteins that are translated on free (cytoplasmic or unbound) ribosomes are destined to function in
the mitochondria, chloroplasts, cytoplasm or nucleus of the cell.
170
what is apolysome
where multiple ribosomes can attach to the same mrna
171
a function of the signal recognition particle (SRP)?
To help translocate polypeptides across the ER membrane
172
When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by:
A signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane
173
Bound ribosomes synthesise proteins mainly meant for
secretion or for use in lysosomes.
174
Free ribosomes produce proteins for use
mainly within the cell.
175
what maintains the primary striucture of a protein
peptide bonds between the subunits
176
what maintains the secondary structure of the protein
It is stabilised by hydrogen bonds between –NH groups (from the peptide bonds) and –C=O groups on another peptide bond, further along in the same chain.
177
what stabilises the tertiary structure
interactions between R groups.
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The polar R groups will be stabilised by interactions such as
ionic interactions between acidic and basic R groups, or hydrogen bonding. In addition, covalent bonds may form between R groups containing sulfur (these bonds are called disulfide bridges). Only the amino acids cysteine and methionine have R groups that contain sulphur.
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what do quaternary proteins often also haev
a non protein moelcualr unit called acofactor or prosthetic group that is tightly attached to their polypeptides
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what is a conjugated protein
a protein with a prosthetic group attached
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What aspects of protein structure are stabilised or assisted by hydrogen bonds?
Secondary, tertiary, and quaternary structures, but not primary structures
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