Structure, Function and Defence Flashcards
1
Q
How many chromosomes does a human have?
A
22 pairs and 2 sex chromosomes
2
Q
What is the difference between DNA and RNA?
A
RNA has a hydroxy group attached its sugar in the place where DNA only has a hydrogen molecule.
3
Q
Name the four nucleic bases
A
Cytosine, thymine, adenine and guanine
4
Q
A nucleotide is made up of which components?
A
Phosphate group, sugar and nucleic base
5
Q
What reaction takes place to join two nucleotides, and what does this look like?
A
Condensation reaction between the hydroxy group and the phosphate group forming a phosphodiester bond. This creates the phosphate backbone of a single strand of DNA.
6
Q
What is base pairing?
A
Two hydrogen bonds form between A and T, three hydrogen bonds form between C and G. This creates the double strand of DNA.
7
Q
What is the transfer of information between DNA and mRNA called?
A
Transcription
8
Q
What nucleotide replaces thymine in RNA?
A
Uracil
9
Q
What enzyme facilitates the unwinding of DNA before transcription?
A
RNA polymerase
10
Q
3 bases in a row can be described as what, and what does each one code for?
A
Codon, an amino acid
11
Q
The codon system can be described as what, and what does this mean for the DNA sequence?
A
Degenerate, meaning only 20 amino acids are coded from 64 possibilities of codons, this results in a lot of DNA sequences coding for nothing.
12
Q
What are the regions called that code for amino acids?
A
Exons
13
Q
When exons are ligated together, they can be mixed up to create different sequences that create different proteins, what is this called and what does it mean for protein synthesis?
A
Alternative splicing, it means that one strand of DNA can code for many different proteins.
14
Q
Where does translation occur, and what does it involve?
A
Ribosomes, tRNA transports amino acids to the mRNA, the tRNA has an anti-codon that base pairs with the codon of mRNA and joins its amino acid to the chain via a peptide bond.
15
Q
What two main groups are present in an amino acid?
A
Amine and carboxylic acid group
16
Q
What is a peptide bond?
A
A condensation reaction that forms a bond between the amine and carboxylic acid group of amino acids to create polypeptides.
17
Q
What is a protein’s primary structure?
A
Sequence of amino acids
18
Q
A protein has how many structures?
A
4
19
Q
Proteins in the lenses in our eyes change as we age, this is an example of what process?
A
Post-translational modification
20
Q
Sickle cell anaemia, CF and haemophilia are all examples of what type of mutation?
A
Point mutations
21
Q
What does autosomal mean?
A
All other chromosomes apart from sex chromosomes
22
Q
Mutations that do not cause any change in the amino acid sequence are called what?
A
Silent
23
Q
What are the three types of mutagenesis?
A
Genetic, chemical and radioactive
24
Q
Intercalating, alkylating and oxidising agents can cause what type of mutagenesis?
A
Chemical
25
What are the three types of missense mutations?
Substitution, insertion and deletion
26
What is a nonsense mutation?
The sequence of nucleotides is changed to a stop codon which prematurely ends the sequence and creates a truncated protein.
27
True or False: mutations in the non-coding region of DNA can also affect the production of amino acids
True
28
Name the organelles found in a typical human cell?
Nucleus, golgi apparatus, mitochondria, endoplasmic reticulum, lysosome
29
What are the four basic tissue types in the human body?
Epithelial, connective, muscular and nervous
30
Name the four major types of epithelial tissue
Columnar, cuboidal, squamous and pseudostratified
31
Name one type of connective tissue
Bone, tendon, fat etc
32
What are the three types of muscle cells?
Smooth, cardiac and skeletal
33
Name two functions of epithelial tissue and where they might be found
Absorption- intestines, barrier- skin, secretion- glands
34
Simple squamous epithelium can be found in what areas of the body?
Pleura, peritoneum, alveoli, capillaries
35
The digestive tract is lined with mainly what type of epithelial tissue?
Simple columnar
36
The oral cavity, anal cavity and vagina are examples of places with mainly which type of epithelial tissue?
Stratified squamous (non-keratinising)
37
The epidermis of the skin is mainly made of what type of epithelial tissue?
Stratified squamous (keratinizing)
38
What type of epithelial tissue is only found in the ureter and bladder?
Urothelium (transitional)
39
What adheres epithelial tissue to the underlying tissue?
Basement membrane
40
Name two endocrine glands
Thyroid, pituitary, pancreatic islets
41
Name two exocrine glands
Salivary and sebaceous
42
Name four functions of connective tissue and what type it relates to
Storage- fat, support/protection- bone, strength- ligaments, movement- cartilage in joints, transport of nutrients- blood vessels, structure- cartilage/bones
43
What is the cell membrane made from?
Phospholipid bilayer
44
Active transport occurs in what direction and requires what?
Against a concentration gradient, it requires energy
45
What is osmosis?
Simple diffusion of water across a membrane, from a high concentration of water to a low concentration of water.
46
What vitamin is involved in blood clotting?
K
47
Name a function of Vit B12 (cobalamin) in the body
Aids the production of DNA, meaning also amino acids, proteins and cells (such as erythrocytes)
48
Folate (folic acid) is essential in pregnancy to prevent what?
NTD such as spina bifida
49
How do the majority of enzymes work?
The active site of the enzyme is complementary to the shape of its desired substrate(s). The substrate(s) bind to this active site, the reaction takes place with the enzyme present, lowering the activation energy needed for the reaction to occur. The products then disassociate so the enzyme can continue to catalyse more reactions.
50
What is metabolism?
Chemical reactions within the body
51
Where does a non competitive inhibitor for an enzyme attach?
Allosteric site
52
What is negative feedback inhibition with enzymes and why is it important?
The product of a metabolic reaction inhibits the enzyme at an earlier stage in the reaction, it is important in maintaining balance of products and reactants.
53
A competitive enzyme inhibitor does what?
Competes for substrate sites, reducing the efficacy of the enzymes and slowing down the rate of reaction
54
Lyases catalyse what type of reactions?
Double bond creation
55
What type of enzymes catalyse condensation reactions?
Ligases
56
What is parenchyma?
Functional tissues of an organ
57
What are the supportive or connective tissues of an organ classified as?
Stroma
58
Name the four stages of tissue repair
Angiogenesis, fibroplasia, granulation and epithelialisation
59
Wound contraction and remodelling are due to what cells?
Fibroblasts
60
What is primary and secondary intention in the context of wound healing?
Primary intention is where the wound edges can be pulled together. Secondary intention is where the wound edges cannot be closed and so the wound has to heal from the base by promoting granulation.
61
What are growth factors?
Hormone-like molecules that stimulate proliferation, differentiation and maturation of cells.
62
Cellular organisms can be split into what two groups?
Prokaryotic and eukaryotic
63
There are three types of multicellular eukaryotes, what are they?
Fungi, animal and plant
64
What difference is there in the genetic DNA storage between prokaryotes and eukaryotes?
Eukaryotes have a nucleus containing chromosomes, prokaryotes only have a naked loop of DNA
65
What is the difference between a gram -ve bacteria cell wall and a gram +ve?
Gram +ve have a thick peptidoglycan layer on the outermost aspect of the cell wall. Gram -ve have a lipopolysaccharide layer
66
What colour do gram -ve bacteria stain?
Red
67
What colour do gram +ve bacteria stain?
Blue
68
Name the 4 different virion structures
Tobacco mosaic, adenovirus, influenza, bacteriophage
69
What genetic material is present in viruses?
Single or double stranded RNA or DNA
70
What is viral tropism?
The ability of viruses to only infect certain types of cells
71
DNA viruses have to infect cells in the S phase of the growth cycle, name an example of a DNA virus
HPV, HSV
72
RNA viruses are not affected by the host cells growth cycle because they transcribe directly or use their own enzymes to produce a form that can be transcribed directly by the host's ribosomes. Name some examples of RNA viruses
RSV, influenza, rhinovirus, SARS
73
What is viraemic dissemination?
Where the viruses is carried to different parts of the body via the lymph and blood
74
What is syncytia?
Multinuclear cells that are created by fusing cells together, caused by viruses such as RSV
75
Viruses can cause host cells to enter endoplasmic reticulum stress because of the demands of replication. This leads to an accumulation of misfolded proteins, how does the host cell respond?
Pauses protein synthesis, degrades misfolded proteins, induces apoptosis as a last resort.
76
Which type of viruses case cell mutation and apoptosis?
Cytopathic
77
Some viruses create a chronic infection, how do they do this?
They have a slower but continuous virion production, they do not destroy or kill the host cell but can elicit long term cellular effects.
78
Viruses that reduce their replication to minimal levels are able to do what?
Create a latency period where the host experiences no symptoms, they will be lifelong and can reactivate to create secondary infections.
79
Oncogenic viruses can transform the host cell causing uncontrollable proliferation, name some examples
He B and C, HPV, EBV
80
What is antibody neutralisation?
The binding of antibodies to viruses which prevents endocytosis or uncoating.
81
What is TRIM21?
A protein that binds to an antibody-antigen complex, marking it for degradation via proteasomes
82
What is antigenic drift?
Mutations in the virus that change the structure sufficiently to evade the adaptive immune system.
83
What is antigenic shift?
Two viruses that both infect a host cell and their genetic material is mixed to create a new virus.
84
What is the purpose of type 1 interferons?
Enhance expression of HLA class I, activate natural killer cells and signals unaffected cells to slow protein synthesis and degrade viral mRNA.
85
Cell development of specific features is called what?
Differentiation
86
Proliferation is what?
Grow in number by cell division
87
Name the 6 stages of the cell cycle
G0, G1, S, G2, Mitosis, Cytokinesis
88
The phosphorylation of proteins in the start of cell growth is facilitated by what enzyme?
Cyclin dependant kinase (CDK)
89
What cell cycle phase does DNA synthesis occur?
S phase
90
The mitosis phase of the cell cycle consists of what phases?
Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
91
What is a haploid cell?
A cell with half the genetic material (e.g. gamete)
92
During the first stage of meiosis, during prophase, sister chromatids (of the same chromosome) align with the chromatids from the other chromosomes, why is this important?
Enables crossing over (swapping) of genetic material which creates genetically distinct chromosomes at the end of meiosis.
93
In the G0 phase, what functions associated with cell growth are happening?
None
94
What happens during G1 phase of the cell cycle?
Cells grow to full size
95
Which phase of the cell cycle includes rapidly producing cell contents?
G2
96
What happens to cyclin once it has been used in the reaction with CDK to activate proteins? Why is this important?
It is destroyed to prevent a chain reaction and uncontrollable proliferation
97
What is the name of the gene transcription factor that needs to be activated for S phase?
E2F
98
What is the relationship between cyclin, CDK and E2F activation?
CDK and cyclin bind to the Rb protein attached to E2F, the Rb protein is then phosphorylated and released from E2F, making it active
99
In which two phases of mitosis do the chromosomes condense and spindle fibres appear and attach to the chromosomes?
Prophase and prometaphase
100
Describe what happens during metaphase?
chromosomesand their copies line up in the centre of the nucleus, spindle fibres attach to sister chromatids
101
During anaphase, the spindle fibres pull what apart?
Sister chromatids
102
What are sister chromatids?
Two identical copies of the same chromosome, formed by DNA replication in S phase, held together by a centromere.
103
Describe what happens during telophase?
Nuclear membrane forms around each group of chromosome, spindle fibres disappear and the chromosomes decondense
104
In which stage of mitosis do the cell membranes split into two identical daughter cells?
Cytokinesis
105
What is the equation for specificity?
TN/(TN+FP). Specificity is negative- SpIN
106
In a screening test with a high specificity and a low sensitivity, what might you expect and what does this mean for people?
People who test positive are most likely to be true positive, people who test negative have a chance of being false negative. There aren't many false positives.
107
What is the equation for sensitivity?
TP/(TP+FN).
108
What is the equation for positive predictive value?
TP/(TP+FP).
109
Name two reasons why cell death (apoptosis) is important
Tissue homeostasis, immune system defense, embryonic development, regulation of viability by hormones
110
Apoptosis is what?
Programmed cell death
111
What is necrosis?
Accidental death of cells caused by outside factors that cause irreversible injury.
112
True or False: apoptosis causes an inflammatory response
False, necrosis causes an inflammatory response
113
True or false: cells undergoing apoptosis shrink rather than swelling
True
114
Briefly describe the process of apoptosis
Latentphase: the cell is marked for death but remains normal. This can last for hours or days.
Execution phase: lasts an hour. The cell membrane and cytoplasm shrink, phagocytes destroy the phospholipid bilayer, the nucleus collapses and the cell fragments into smaller membrane bound vesicles that are engulfed by phagocytes.
115
Name some examples of cells that might be marked for apoptosis
Excess cells (e.g. neurons in embryonic ganglia)
Obsolete cells (e.g. webbing in between digits in embryo)
Developmentally defective cells (e.g. immature T cells in the thymus that cannot interact with the bodies MHCs)
Cells without correct checkpoints in cell division
Pathogen-infected cells
Chemotherapeutic apoptosis
Cells with damaged components.
116
Ischaemia causes what type of necrosis and what does it look like?
Coagulative necrosis, firm, dry and slightly swollen
117
Colliquative necrosis is seen as a primary event in what organ?
Brain
118
Describe the process and result of colliquative necrosis
Lysosomal enzymes digest cellular components and a leaves an accumulation of semi-fluid.
119
Caseous necrosis is seen as a result of what disease and what does it look like?
TB, thick pus filled mass surrounded by macrophages and inflammation
120
Syphilis infection causes what type of necrosis and what does it look like?
Gummatous, firm and rubbery dead tissue
121
What types of necrosis happen in wet and dry gangrene, respectively?
Wet gangrene = liquefactive necrosis from bacterial infection
Dry gangrene = coagulative necrosis from anoxia
122
What is fibrinoid necrosis?
Small blood vessels are destroyed in autoimmune conditions or malignant hypertension. It can only be seen in a histology sample
123
Fat necrosis can occur from enzymes released from what organ?
Pancreas
124
Blood vessel rupture causes leakage of red blood cells into dead tissue causes what type of necrosis?
Haemorrhagic necrosis
125
Contrast the difference between ischemia and infarction
Ischemia is the deprivation of blood (oxygen) to the affected tissue.
Infarction is the necrosis of that tissue as a result of ischemia.
126
During ischemic events, how does the mitochondria in affected cells react and how does this affect the cells?
Switch from aerobic to anaerobic metabolism, this produces less ATP and lactic acid. Lactic acid reduces the pH of the cell. Less ATP causes ion pumps to fail disrupting osmotic equilibrium.
127
Describe the molecular basis of a reperfusion injury
Free radicals created during anaerobic respiration are converted to superoxides which cause cell membrane, protein and DNA damage.
Influx of leukocytes to inflammation area creates further cellular injury.
Damage to the calcium ion movement system in ischemia causes a toxic build up of calcium in the cell. This causes hyper-contracture in the heart.
128
Creatinine kinase (MB) is released by what organelles in the cell during ischemia?
Nucleus and mitochondria
129
Troponin (I, C and T) are found where?
They are proteins found in muscles and help the interaction between actin and myosin filaments in contraction.
130
Describe the process of glycolysis before the Kreb's cycle
Glucose is broken down into two pyruvate molecules, it is anaerobic and there is a net gain of two ATP molecules
131
What does pyruvate become in the presence and absence of oxygen, respectively?
Acetyl-co-A, lactate
132
What metabolic process causes the symptoms of ischemia?
calcium influx, potassium efflux, reduced cell pH due to lactic acid
133
Put in order of presence in the bloodstream during ischemia: proteins, ions, lactate. Explain your answer.
ions- efflux of K+ happens early in ischemia. lactate- anaerobic respiration leads to lactate production. proteins- cell death leads to leakage of proteins into the blood.
134
Ischaemic modified albumin is a cardiac marker currently being researched, at what time after ischemia could this be detected?
a few minutes
135
What is the peak time range for levels of troponin I?
12-24 hours
136
When can levels of troponin first be detected after ischemia?
4 hours
137
What is a sensitive marker of an MI and why?
Myoglobin, if it's not elevated then it can rule out an MI because false negatives are not likely. It's specificity is low though because it is present in skeletal cells as well as cardiac cells, meaning false positives are more likely.
138
What is a specific marker of an MI and why?
Troponin, if it's positive then it is likely to be an MI because false positives are unlikely.
139
Where is calcium stored in muscle cells?
Sarcoplasmic reticulum
140
Muscle contraction is dependent on what ion?
Calcium
141
In smooth muscle, what protein does calcium bind to to create a complex that activates a kinase enzyme?
Calmodulin (CaM)
142
What is the name of the kinase enzyme involved in smooth muscle contraction?
Myosin light chain kinase
143
Which two muscle proteins are largely involved in muscle contraction?
Actin and myosin
144
What aspect of the nervous system controls smooth muscle function?
ANS
145
What aspect of the nervous system controls skeletal muscle function?
Somatic
146
Which form of muscle cell, skeletal or smooth, is multinucleated?
Skeletal
147
Which form of muscle cell, skeletal or smooth, contains gap junctions?
Smooth
148
The presence of which ion dictates the contraction and relaxation of all muscle?
Calcium
149
In smooth muscle, where does the majority of calcium come from?
Extra-cellular fluid
150
What is the main energy producing reaction in cells?
ATP hydrolysis into ADP + Pi
151
During a myocardial infarction, how would levels of ATP change?
More AMP and less ATP, showing the cells were in a state of energy stress.
152
The oxidation reaction converting NAD+ to NADH releases what gas?
CO2
153
For every one molecule of glucose in the Kreb's cycle, how many ATP are formed?
2
154
Where does oxidative phosphorylation occur?
Mitochondria
155
What molecules are importantly created during the Kreb's cycle to be used for H+ ions in the electron transport train?
NADH and FADH2
156
Briefly, how does the electron transport chain work?
Proteins in the surface of the mitochondria reduce NADH and FADH2, releasing energy and H+ ions.
The energy gained from the reduction reaction is used to pump H+ out of the membrane.
H+ ions then move down the concentration gradient through the ATP synthase protein, the energy from the rapid movement of the ions is use to phosphorylate ADP into ATP.
157
What are the four steps of cellular respiration?
Glycolysis, Pyruvate to Acetyl-co-A, Kreb's cycle and oxidative phosphorylation.
158
What has a higher energy yield: fat or glucose?
Fat
159
How is fat stored in the body?
As triglycerides made from three fatty acid chains.
160
How are triglycerides transported in the blood?
They are broken down in lipolysis into free fatty acids which are a single chain.
161
What is palmitate?
A fatty acid
162
What is glycogen?
The storage molecule of glucose
163
Describe the difference between a lymphocyte and a leukocyte
Leukocytes are a term used to describe all white blood cells whereas lymphocytes are specifically antibody producers.
