Transcript 9-3_IMMS1_TomAtkinson_RhonaMcMillan_EmilyWatson

phase1
Rhona, Tom, Emily
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aims
• Cover basic information form IMMS
• Cover things likely to come up in exams
• Look at areas where there is often confusion
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introduction
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Cells
Homeostasis
Molecular Building Blocks
DNA and RNA
Mitosis and Meiosis
Genetic Diseases
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Cells
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Cytoskeleton
• Microtubules- tubulin
• Microfilaments- Actin
• Intermediate filaments- desmosomes
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Membrane
- Phosholipids:
- Sphingophospholip
ids
- Glycerophospholipi
ds
- Cholesterolmembrane fluidity
and signalling
system
- Glycolipids
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Function of cell membrane
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Physical boundary
Regulation of substance movement
Receptors for cell to cell signalling
Attachment to extracellular matrix
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Membrane proteins
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Receptors
Enzymes
Transport proteins
Cell adhesion molecules
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Movement across membrane
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Homesostasis
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Control of internal body environment
Autocrine
Paracrine
Endocrine
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Water
• 60% of body weight 40 intracellular 20 extra
• Extracellular: interstitial, plasma, transcellular
(digestive)
• Regulation: Vasopressin
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Definitions
• Osmosis: is the spontaneous net movement of
solvent molecules through a semi-permeable
membrane into a region of higher solute
concentration
• Osmolality: The amount of solute in a solution
• Oncotic pressure: Pressure exerted on water
movement by solute
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Molecular building blocks
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Protein structures
• Primary: linking of amino acids
• Secondary: alpha helix's, beta sheets (H
bonds)
• Tertiary: Interactions between side chains
• Quaternary: joining of polypeptides
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DNA and RNA
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Features of DNA
Degenerate
Almost universal
Unambiguous
Non-overlapping
DNA Replication
Semi-conservative
Enzymes:
• Topoisomerase
• Helicase
• DNA polymerase
• DNA ligase
Okazaki fragments
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Transcription and Translation
DNA (gene)
Nucleus
Transcription
mRNA
mRNA
Ribosome
Translation
Protein
Introns and Exons
Introns are non-coding regions
Exons are coding regions
Codons and mistakes
Start codon: AUG
Stop codons: UAG, UGA, UAA
Single nucleotide polymorphism can result in…
• Mis-sense: Codes for a different aa
• Non-sense: Doesn’t code for an aa. Acts as a
stop codon
Mitosis and Meiosis
Mitosis: Cell division in which two identical daughter
cells are produced
Meiosis: Cell division in which the chromosome
number is halved
Mitosis: Cell cycle
Mitosis: Stages
PMAT
Prophase
(Prometaphase)
Metaphase
Anaphase
Telophase
Mitosis: Stages
Prophase: Chromatin
condenses to chromosomes
Prometaphase: Nuclear
membrane disintegrates.
Chromosomes attach to
microtubules
Mitosis: Stages
Metaphase: Chromosomes
line-up on equatorial plate
Anaphase: Sister chromatids
are separated and pass to
opposite poles
Mitosis: Stages
Telophase: Nuclear membranes
form, chromosomes unfold
Cytokinesis: Cell divides
Mitosis under the microscope
Meiosis
PMA(T) X2
Meiosis 1
• Where chromosome number is halved
• Crossing-over between non-sister chromatids
(M1)
Meiosis 2
• Sister chromatids separate
• Haploid cells produced
Meiosis
Genetic diversity
• Crossing over
between nonsister chromatids
• Random
assortment on
metaphase plate
Gametogenesis
Gametogenesis: Formation of haploid gametes
in precursor cells (in testes/ovaries)
Differences between sexes:
• Male: Meiotic division starts at puberty
• Female: Meiosis 1 completed at ovulation,
Meiosis 2 if fertilisation occurs
Gametogenesis
Mendel's second law (Law of independent
assortment):
Alleles of one gene sort into gametes
independently of the alleles of another gene
Gonadal Mosaicism
Gonadal mosaicism: mutation in primordial
germ cell. All gametes from it are affected
Mother
Genetic Diseases
• Phenotype = The appearance of an individual
resulting from interaction of the environment
and genotype
• Genotype = The genetic constitution of an
individual
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Autosomal Dominant
• Manifests in heterozygous
state
• Both males and females are
effected equally
• 50% chance of inheriting
disorder
• e.g. Achondroplasia, Marfan
syndrome, Huntington’s
disease
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Sex Linked
• Males = XY Females = XX
• X linked genes never pass from father to son
• Males can never be carriers
X linked Dominant:
• Expressed and transmitted
by both sexes
• Occurs twice as frequently
in females as males
• Difficult to distinguish from
AD
• e.g Hypophostphataemia
rickets
X linked Recessive :
• More males than females show
the phenotype
• Affected male would usually
have no effected offspring but
all the daughters would be
carriers
• e.g Haemophilia, Duchenne
muscular dystrophy
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Sex Linked
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Lyonization
• Process of x chromosome inactivation
• One of the two X chromosomes in every cell in
a female is randomly inactivated early in
embryonic development.
• Via methylation
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Knudson’s 2 Hit Hypothesis
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Multifactorial Disease
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Quiz Time
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Quiz Time
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Quiz Time
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The end!
Thank you for listening!
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