Advanced Notice Article Flashcards

Question

What are pigment granules?

Answer 1

- Small, sub cellular membrane-bound vesicle - Contains pigment and/or pigment precursor molecules

Answer 2

- Multiple sources, including: - endoplasmic reticulum - coated vesicles - lysosomes - endosomes

Answer 3

- Melanocytes form temporary pseudopodia = carry melanosomes from centre of cell to edge of cell - increases cells effectiveness at absorbing light - process occurs slowly in response to exposure to UV light - UV light = new melanosomes produced - Transferred to adjacent keratinocytes in skin - Melanocytes position themselves by nucleus, closest to UV light = protects genetic material against harmful effects of UV radiation

Answer 4

- Radial and circular muscles (antagonistic muscles) - Control the diameter of the pupil

Answer 5

- Stimulated by sympathetic nervous system - SNV usually increases activity (fight, fright, flight) - Post ganglionic NT = noradrenaline

Answer 6

- Stimulated by parasympathetic nervous system - PNS usually decreases activity (rest and digest) - Post ganglionic NT = acetylcholine

Answer 7

- The physical observable characteristics that are expressed in an organism - Affected by both genotype and environment - Includes biochemistry, physiology, morphology and behaviour

Answer 8

- The combination of alleles present in a cell or organism - Heterozygous, homozygous recessive or homozygous dominant

Answer 9

- Controlled by several genes - Usually show continuous variation (e.g.: height, mass, skin colour)

Answer 10

- Organisms internal or external environment can influence gene expression patterns - Levels or regulatory proteins or transcription factors affected in response to environmental stimuli (light, chemicals, drugs, hormones)

Answer 11

- Some enzymes are activated in response to UV radiation - enzymes increase expression of melanin-producing genes - therefore increase production of melanin - leads to skin pigmentation

Answer 12

- Cytophagocytosis - Direct Membrane Fusion

Answer 13

- A melanocyte dendrite is phagocytosed - Forms a phagolysosome - Melanin granules disperse from phagolysosome through the cytoplasm of keratinocytes

Answer 14

- Plasma membranes of both cells fuse - Creates a nanotube which allows the passage of melanosomes

Answer 15

- Biochemical structure (i.e. DNA) - Physical shape and size - Sequence of genes - Gene loci - Centromere position

Answer 16

- Different origins (one maternal, one paternal) - Different alleles

Answer 17

Position of a gene on a chromosome

Answer 18

- A form of albinism involving eyes, skin and hair

Answer 19

- Caused by mutations in several genes (polygenic) that control synthesis of melanin within melanocytes - Seven types of Oculocutaneous albinism described - All caused by disruption of melanin synthesis - All autosomal recessive disorders

Answer 20

- In humans, OCA2 gene located on long arm of chromosome 15 - Most common type of albinism caused by mutation of P gene - Mutations in OCA2 cause type 2 Oculocutaneous albinism

Answer 21

- OCA2 codes for human equivalent of mouse p (pink-eyed) gene - People with OCA2 usually have fair skin - Usually pale blonde to golden, strawberry blonde or even brown hair - Usually blue eyes

Answer 22

- Yellow hair - Pale skin - Blue, grey, hazel eyes

Answer 23

- Coded for by OCA2, pigment can develop in freckles or moles - Also known as melanocyte-specific transporter protein OR pink-eyed dilution protein - Found in melanocytes and retinal pigmented epithelium

Answer 24

- intrinsic membrane protein - Involved in transport of tyrosine into melanocytes

Answer 25

- A protein ligase involved in DNA repair regulation - Protein ligases important in cell cycle control, controlling breakdown of cyclins and CDK inhibitor proteins

Answer 26

- Mutation in HERC2 gene adjacent to OCA2 = affects OCA2's expression in iris - Common to nearly all people with blue eyes - Are 15 single nucleotide polymorphic forms of HERC2 gene (germline single DNA-nucleotide substitutions) which determine iris pigmentation

Answer 27

number of polymorphic gene loci ______________________________________ total number of loci (no units as is a ratio)

Answer 28

- Large regions of non-coding DNA which are removed from pre-mRNA before it is translated - Removed during post-transcription modification (occurs in nucleoplasm = converts pre-mRNA to mature mRNA)

Answer 29

- Transcription - Post transcription modification - RNA splicing - Translation - Post translation modification

Answer 30

- Ensures genes are only expressed when are where required for required duration - Determines cell differentiation, organism development and adaptability of organism

Answer 31

- Control of insulin expression (blood plasma glucose regulation) - Control of cyclin expression in eukaryotic cell cycle - Control achieved by DNA methylation and histone coat modification

Answer 32

- Epithelial and epidermal barriers protect the body from pathogens and from other environmental stresses - Also separate different internal organs with a unique cellular structure and chemical composition

Answer 33

CILIATED EPITHELIUM - specialised tissue that lines airways - Small projections (cilia) sweep mucus, dust and bacteria upwards and away from the lungs with the epithelium itself

Answer 34

EPITHELIUM - A type of body tissues - Forms the covering on all internal and external surfaces of the body - Lines body cavities and hollow organs - Is the major tissue in glands

Answer 35

- Line the gut, airways and reproductive system - Consists of epithelial cells and mucus-secreting goblet cells - Contains lots of glycoproteins with long carbohydrate chains (glycocalyces) such as mucin

Answer 36

- Mucus in trachea, bronchi and bronchioles traps inhaled viruses, bacteria, pollen and dust - Particles moved towards back of throat by wafting of cilia - Mucus and trapped particles swallowed or expelled by coughing up mucus - Ciliated epithelial cells have motile cilia = beat and move in wave-like manner = moves mucus along airway

Answer 37

- WBC produced continuously in bone marrow - Remove dead cells and invasive microorganisms (non-specific immune response) - Move in amoeboid movement to site of infection and attach to pathogens - CSM of phagocyte extends out and around pathogen = forms pseudopodia = engulfs it by endocytosis - Phagosome fuses with lysosome = phagolysosome = Hydrolytic enzymes from lysosome digest pathogen = hydrolysis reactions of biochemical components of pathogen)

Answer 38

- T cells activated when encounter and bind to specific antigen on surface of antigen-presenting cell (clonal selection) - APC = macrophage, infected body cell or pathogen itself - Activated T cells divide by mitosis (clonal expansion) = increase in number = genetically identical daughter cells - Activates T-helper cells bind with complementary receptors on surface membrane of specific B-lymphocytes - On binding, T-helper cells release signalling proteins = activate B lymphocytes

Answer 39

Release cytokines (hormone-like signals) to stimulate: - Maturation of B-lymphocytes into plasma B-cells - Production of memory B cells - Activation of cytotoxic T cells - Increased rate of phagocytosis

Answer 40

- Patrol body in search of APCs - Attach to foreign substances on cam of infected cells - Secrete toxic substances = kill infected body cells and pathogen inside - Perforins secreted by T killer cells punch hole in csm of infected cells = toxins enter

Answer 41

- B lymphocytes with correct cell surface antibodies recognise antigen and bind to it (clonal selection) - Binding --> antigen-antibody complex - Bdining along with cell signalling molecules produced by T helper cells activates B lymphocyte - Activated = B cells divide repeatedly by mitosis = produces many clones of original activates B cell (clonal expansion)

Answer 42

- Effector cells = differentiate into plasma cells = produce specific antibodies to combat non-self antigens - Memory cells = remain in blood = allow faster immune response to same pathogen in future

Answer 43

- Layer under conjunctiva, continuous with sclera - Focuses light onto retina - Main structure responsible for refraction of light rays onto retina

Answer 44

- Localised response to pathogens at site of wound - Result = pain, swelling, heat and redness of tissue - Mast cells activated in damaged tissue - Mast cells release histamine, cytokines, serotonin and prostaglandins

Answer 45

- Make arterioles dilate (vasodilation) = increased blood flow to area - localised redness, increased pain sensitivity and heat (higher temp prevents pathogens reproducing) - Make arteriole walls more leaky = more plasma forced out = increased tissue fluid formation = soreness, swelling (oedema) and pain

Answer 46

- (e.g.: Interleukin 1 and interleukin 6) - Attract phagocytes to wound = phagocytosis = destruction of pathogens - Also stimulate liver to release proteins = bind to surface of bacteria and damaged host cells = promote phagocytosis by macrophages

Answer 47

- Make arterioles dilate and more leaky - Some plasma proteins leave blood

Answer 48

- T lymphocytes produce an immune response when exposed to a specific antigen - T lymphocytes only bind to a specific antigen if its present on surface of APC - Once surface receptor of T lymphocyte binds to specific complementary antigen on APC it becomes sensitised - It starts dividing to produce clones of cells

Answer 49

- Most common types = macrophages and dendritic cells - Less common = neutrophils

Answer 50

- Produced in bone marrow, mature in thymus - Mature T cells have specific cell surface receptors - T cell receptors - Receptors have similar shape ton antibodies and each is specific to particular type pf antigen

Answer 51

Type 1 - Spreads by oral contact - Causes infections in or around mouth (oral herpes or cold sores) - Can cause genital herpes - Most adults infected with HSV-1 Type 2 - Spreads by sexual contact - Causes genital herpes

Answer 52

- An intense inflammatory response, triggered by viral infection of corneal stroma - If left untreated, chronic inflammatory response --> formation of lesions, scarring and eventually blindness

Answer 53

- DNA virus within nucleocapsid - Matrix (called the tegument) = made up of proteins and mRNAs = allows virus to evade immune response of host cells and facilitate its replication once its invaded host cells - Envelope = lipid bilayer = contains virally encoded glycoprotein spikes = important for viral entry

Answer 54

- At least 12 types of glycoproteins with diverse shapes/sizes reported on surface of HSV - Facilitate viral entry into host cells by interacting with receptors on host cell surface (viral attachment) - Glycoproteins also interact with other glycoproteins - Glycoproteins fuse viral envelope with host cell membrane = enables delivery of viral content into cell

Answer 55

- Stores blood )to be released in times of hypovolemic shock) - Removes old erythrocytes from circulation - Acts in similar way to lymph node = filters blood plasma - Contains high number of B-lymphocytes and monocytes - Produces all types of blood cells during fatal life - Produces opsonins - Releases neutrophils following myocardial infarction - Involved in recycling of iron from old erythrocytes and breakdown (hydrolysis) of globin chains of Hb

Answer 56

(Some TF drains into lymph capillaries) - Separate from circulatory system - Have closed end and large pores = allow large molecules to pass through - Larger molecules that cannot pass through capillary wall enter lymphatic system as lymph via small, one-way valves in lymph vessel walls

Answer 57

- Lymph moves along larger lymph vessels due to compression (from skeletal muscles contracting) - Valves prevent backflow - Lymph re-enters DCS through subclavian vein - Any plasma proteins that escaped from blood = returned to blood via lymph capillaries - Plasma proteins not removed from TF = lower WP of TF = prevents reabsorption of of water into blood - After digestion, lipids transported from intestines to bloodstream by lymph system

Answer 58

- Hydrostatic pressure forces small, soluble molecules out of blood in capillary via fenestrations in capillary wall - Plasma proteins remain in blood = creates WP between capillary and tissue fluid - Overall movement of water = out of capillaries, into tissue fluid

Answer 59

- Hydrostatic pressure in capillary reduced = less liquid forced out of capillary - WPG between capillary and tissue fluid remains same as at arteriole end = water begins to flow back into capillary from tissue fluid via osmosis - Overall = more fluid leaves capillary than returns = tissue fluid left behind to bathe cells

Answer 60

- Pressure at arterial end is greater - Forces larger volume of fluid out of capillary - Fluid accumulates = causes oedema

Answer 61

- Occurs in development of specialised cell - Enables unicellular organisms to develop specialised functions through specific areas of their cell - E.g.: nucleus region contains DNA molecules, compartmentalisation of ATP = produces area formed by endosymbiosis of mitochondria

Answer 62

- Enables the cells in a tissue to function more efficiently as they develop specific adaptations for that role - Development of distinct specialised features occurs by differentiation

Answer 63

- Change in shape of cell - Change in organelles the cells does or doesn't contain - Change in chemical composition of cell (e.g.: presence or increased conc of a specific protein, such as melanin in melanocyte, mucin in goblet cell, haemoglobin in erythrocyte)

Answer 64

- Virus-specific T-lymphocytes enter cornea in significant numbers following HSV infection - Memory T-cells remain in cornea after virus was eliminates (likely to ward off future reinfection)

Answer 65

- A group of similar cells - Consisting of one or more than one cell type - With any extracellular material they secrete - Which are specialised to carry out a specific function - e.g.: squamous epithelium, ciliated epithelium, xylem tissue, phloem tissue, nervous tissue

Answer 66

- Plasma - Lymph

Answer 67

- A target therapy generated for specific viral antigens - Antigens identified as immune target presented by APCs to T-lymphocytes along with other molecules that stimulate their growth and activation - Those T-cells then isolated from donor and expanded in culture to generate more VSTs - Some cases = cells created from blood samples of patients who have recovered from viral infections

Answer 68

P = frequency of dominant allele Q = frequency of recessive allele P^2 = frequency of homozygous dominant genotype Q^2 = frequency of homozygous recessive genotype 2pq = frequency of heterozygous genotype

Answer 69

Relative frequency of an allele )variant of a gene) at a particular locus in a population, expressed as a fraction of percentage

Answer 70

- A section of DNA that codes for a single polypeptide chain

Answer 71

- Phenotypic variation due to combination of genetic and environmental factors - e.g.: recessive allele causing sickle cell anaemia = high frequency in populations where malaria present as heterozygous recessive individuals are resistant to malaria - Complete phenotype of an organism determined by expression of its genotype and interaction of environment Phenotype = Genotype + environment

Answer 72

- Levels of regulatory proteins or transcription factors can change in response to environmental stimuli (e.g.: light, chemicals like drugs and hormones) - Some enzymes activates in response to UV radiation = increase expression of melanin-producing genes

Answer 73

- Control of gene expression by factors OTHER THAN an individual's DNA sequence - Involves switching on and switching off genes WITHOUT changing the actual genetic code

Answer 74

- Methylation of DNA = chemical addition of -CH3 groups to the cytosine NCBs - Histone modification = Via acetylation of amino acid tails - These modifications are called epigenetic tags

Answer 75

- All the epigenetic tags in an organism - Epigenome can undergo changes due to smoking, stress, exercise ad diet - Internal signalling fro, body's own cells can also cause modifications to occur - Epigenetic modification is independent (e.g.: DNA methylation or histone modification in one area is NOT linked to modification in another)

Answer 76

- Chemical modification of histones and DNA controls how tightly the DNA is wound around them (as intermolecular bonding between histones and DNA changes) - DNA wound more tightly in certain area = genes on this section of DNA are 'switched off' (as gene and promoter regions more hidden from transcription factors and RNA polymerase) - Histone modification is reversible = can be different in different cell types and can vary with age

Answer 77

- Methyl groups directly added to DNA to alter gene expression - Usually involves direct addition of methyl group to cytosine bases - Methylation of DNA suppresses transcription of affected gene by inhibiting binding of transcription factors and enzymes needed for transcription (e.g.: RNA polymerase) - Cells use mechanism to lock genes in 'off' position = gene repressed / inactivated - DNA methylation affected by many environmental, lifestyle or age-related factors

Answer 78

- Acetyl groups added to lysine amino acids on histone proteins - Lysine has positively charged R group - Forms ionic bonds with negatively charged sugar-phosphate backbone of DNA - Helps DNA coil tightly around histone protein core

Answer 79

- Adding acetyl groups to lysine residues removes positive ion = removes bond between histone protein and DNA - SO DNA less tightly wrapped around histones - RNA polymerase and transcription factors can bind more easily = gene expression can occur - Gene = activated

Answer 80

- Removal of acetyl groups - Makes lysine return to its [ositively charged state - So stronger attraction to DNA molecule - So inhibits transcription - So stops gene expression

Answer 81

- E.g.: during gamete production - DNA in parent cell underuse de-methylation BUT often methyl groups not removed = present in DNA in sperm of oocytes - MAYBE AS epigenetic changes occur in response to environmental factor = beneficial for epigenetic changes to also occur in daughter cells (e.g.: gametes) = adapted for environmental factor - Modifications to epigenome in one generation passed onto next generation at cellular or whole organism level = Epigenome is heritable

Answer 82

- Receptors (e.g.: hormone receptor such as insulin) - Immobilised enzyme (e.g.: maltase) - Channel proteins (e.g.: sodium ion channels) - Voltage-gated channels (e.g.: potassium ion channels) - Electron carriers (e.g.: cytochrome) - Carrier-Protein Pump (e.g.: sodium-potassium ion pump) - Cell-to-cell recognition (e.g.: glycoprotein-antigen) - Anchor proteins - Proteins enabling cell adhesion

Answer 83

- Light absorption - Regulation of oxidative stress - Immune regulation - Formation of new blood vessels

Answer 84

- Infrared light - Visible light - Ultraviolet radiation (in front of eye, melanocytes block 99.9% of these wavelengths)

Answer 85

- Eumelanin (brownish black) - Pheomelanin (reddish yellow)

Answer 86

- Amphoteric = can donate or accept electrons - Zwitterion formed (as COO- group or NH3+ group) = can be either positively or negatively charged amino acid - Amphoteric and zwitterions = act as buffers as add or remove protons into environmental solution = alter pH

Answer 87

- 20 naturally occurring amino acids - Amino / Amine group = NH2 - Carboxyl group = COOH - R group (or side chain) varies between amino acids

Answer 88

- Codes for by UAC or UAU in mRNA = example of degenerate codon - Recessive allele for tyrosine --> albinism - Residual group likely specific for tyrosinase active site - R group has 'OH' = can form hydrogen bonds - R-group is polar = R-group is hydrophilic (but not the amino acid itself) - Means tyrosine is soluble in water

Answer 89

Number and sequence of a chain of amino acids joined by a series of condensation reactions, forming peptide bonds

Answer 90

Local folding of the polypeptide chain into alpha helices and/or beta pleated sheets, held in place by hydrogen bonds

Answer 91

Three-dimensional further folding pattern of a polypeptide chain due to residual groups, resulting in a globular or fibrous protein

Answer 92

2 or more polypeptide chains, OR 1 polypeptide chain and a prosthetic group

Answer 93

- Peptide - Covalent (which are peptide bonds)

Answer 94

- Peptide - Hydrogen bonds between NH of amino group of one amino acid and C=O of carboxyl group of another amino acid - Covalent (which are peptide bonds)

Answer 95

- Hydrogen bonds form between NH of amino group in chain and C=O of carboxyl group (usually 4 amino acids further down polypeptide chain)

Answer 96

- Peptide - Additional hydrogen bonds between functional groups which form dipoles in a single ppc - Hydrophobic interactions between non-polar R-groups in same ppc - Disulphide bonds between 2 cysteine R-groups of same ppc - Ionic bonds between polar R-groups of same ppc - Covalent (which are peptide bonds)

Answer 97

- Peptide - Hydrogen bonds can form between same ppc or different ppc's - Hydrophobic interactions between non-polar R-groups between same or different ppc's - Disulphide bonds between 2 cysteine R-groups of same or different ppc's - Ionic bonds between polar R-groups in same or different ppc's - Covalent (which are peptide bonds)

Answer 98

- presence of melanosomes - higher number of mitochondria - increased RER (size and number) = more extensive and more cisternae - Increased number of Golgi apparatus - Higher number of 80s ribosomes as is a eukaryotic cell

Answer 99

- Increased concentration of melanin - Higher quantity of mRNA for the melanin

Answer 100

- Extensions / protrusions of csm - Projections of cytosol to form dendrites - Irregular shape

Answer 101

- Membrane-bound vesicle containing melanin - Buds off Golgi vesicle

Answer 102

- Protective layer, refracting light rays as they enter the eye

Answer 103

- Consists of radial muscles and circular muscles (antagonistic) - Controls intensity of light that passes through pupil PUPIL REFLEX: - When pupil constricts, circular muscles contract - When pupil dilates, radial muscles contract

Answer 104

- Transparent disc that can change shape to focus light rays on the fovea of the retina - Carries out accommodation, controlled by ciliary muscles and suspensory ligaments

Answer 105

- Light rays are refracted onto the retina - Contains photoreceptors (rod cells and cone cells) to absorb light - Fovea has highest concentration of cone cells

Answer 106

- Collection of neurones that carries nerve impulse between photoreceptors on retina and occipital lobe

Answer 107

- Point at which light enters eye - Constriction or dilation of pupil controlled by radial and circular muscles in iris = pupil reflex = accommodation

Answer 108

Pigment = rhodopsin Type of vision = black and white Number of cells that synapse with 1 bipolar neurone = 2 or more (multiple) Sensitivity to light = higher Visual acuity = lower

Answer 109

Pigment = iodopsin Type of vision = colour Number of cells that synapse with 1 bipolar neurone = 1 Sensitivity to light = lower Visual acuity = higher

Answer 110

- UV - Heat (damages bonds) - Hydrogen peroxide = apoenzyme (needs calcium ions), broken down by catalase

Answer 111

- Highest energy as highest frequency = more likely to cause damage

Answer 112

Different types of bulk transport: - Phagocytosis (adapted) - Spontaneous annealing of membranes (adapted) - Endocytosis (adapted) - Exocytosis and phagocytosis (adapted)

Answer 113

- Active process - Uses ATP as cytoskeleton involved - More tubulin produced = more protein synthesis needed = more ATP needed

Answer 114

A short length of DNA that codes for the production of a specific polypeptide chain

Answer 115

A gene variant that codes for the variation of the gene

Answer 116

An allele which is always expressed if present in the genotype, as only 1 copy is needed in the genotype to be expressed in the phenotype

Answer 117

An allele that is only expressed in the phenotype if two of them (2 recessive alleles) are present in the genotype

Answer 118

The combination of all alleles present in a cell of individual

Answer 119

Observable characteristics expressed due to the organism's genotype

Answer 120

A genotype made up of 2 alleles of the same type

Answer 121

A genotype made up of 2 different alleles, one dominant and one recessive

Answer 122

A phenotype that is controlled by a single gene

Answer 123

A phenotype that is controlled by 2 or more genes

Answer 124

- Gene located on chromosome 15 - Crucial role in production melanin (especially brown-black eumelanin)

Answer 125

- OCA2 gene codes for protein that regulated melanosomes which produce melanin - Mutation = affects quantity and distribution of melanin in iris - 2 functional copies of OCA2 = brown eyes - 2 non-functional copies of OCA2 = blue of green eyes (as less eumelanin produced = underlying blue structural colour more visible)

Answer 126

- Specific region of HERC2 gene regulates expression of OCA2 - Mutations in HERC2 affect expression of OCA2 - A variant of HERC2 more common in people with blue eyes

Advanced Notice Article Flashcards

(150 cards)