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Introduction to the Medical biology. Structural and functional organization of a cell.

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Title: Introduction to the Medical biology. Structural and functional organization of a cell.


1
Introduction to the Medical biology. Structural
and functional organization of a cell.
  • Autor Iryna Pryvrotska

2
Questions to answer
  • General and medical Biology as the sciences.
  • Characteristics of living things.
  • Levels of living organization.
  • The cell theory in its modern form.
  • Cellular level of life organization
  • -prokaryotic and eukaryotic cells
  • -the differences between plant and animal
    cells.
  • The main components of eukaryotic cell.
  • Reproduction on cellular level

3
Characteristics of living things.
  • use energy have a metabolism- the building up
    and breaking down of chemicals
  • grow and develop become larger and more complex
  • respond to their surrounding
  • reproduce- produce offspring that are similar to
    the parents  
  • have the chemicals of life, carbohydrates,
    proteins, lipids and nucleic acids (genetic
    material)  
  • have cells
  •       The fundamental characteristics of living
    things
  • reproduction (self-reproduction), which is the
    process that gives rise to offspring
  • genes (self-renewal) are the units of
    inheritance, passed prom parent to offspring,
    that control many daily functions.
  • Finally, populations of living organisms adjust
    to environment variations through evolution, a
    change in the traits of a species over time
    (self-regulation).

4
CELLS- are the basic units of structure and
function in living things.
  • ROBERT HOOKE- first to look at cells looked at a
    thin section of cork
  • ANTON VAN LEEUWENHOEK made his own lenses made
    first compound microscope drew pictures that we
    can still identify today
  • Schleiden concluded all plants are made of
    cells
  • Schwann concluded all living things are made up
    of cells

5
Three main levels of living organization
  • Microsystem - molecular, subcellalar, cellular
    levels
  • Mesosystem tissular, organellic, organismic
  • Macrosystem of population and species,
    biocenotical, biosheric.

6
Cell theory
  • All organisms are composed of one or more cells,
    within which the life processes of metabolism and
    hereditary occur.
  • Cells are the smallest living things, the basic
    unit of organization of all organisms.
  • Cells arise only by division of a previously
    existing cell.

7
What are the cells?
  • Basic unit of life
  • Properties
  • - biomembrane enclosed
  • - four biomolecules proteins, polysacharides,
    nucleic acids, lipids
  • - metabolism and energy transformation
  • Two major types
  • Prokaryotic lack defined nucleus
  • Eukaryotic contain membrane bound nucleus

8
What are the differences between prokaryotic and
eukaryotic cells?
  • Kindoms
    Kindoms
  • 1. Monera (Fubacteria)
    1. Protista
  • 2. Archaea (Archaebacteria)
    2. Fungi


  • 3. Plantae


  • 4. Animalia
  • Characteristics
    Characteristics
  • 1. Lack a nuclear membrane 1.
    Have a nuclear membrane
  • 2. Have no membrane bound organels 2. Have
    membrane bound organels
  • Current evidence indicates that eukaryotic
    evolved from prokaryotic between 1 and 1,5
    billion years ago

9
What are the differences between plant and animal
cells?
  • 1. Chloroplast 1.
    Centriole
  • 2. Vacuole 2.
    Lysosome
  • 3. Cell wall

10
Survey of organelle structure and function
  • Cytoplasm and cytosol
  • Plasma membrane
  • Mitochondria and plastids
  • Endoplasmic reticulum
  • Golgy apparatus( complex)
  • Lysosomes
  • Nucleus
  • Vacuoles
  • Ribosomes
  • Centrioles
  • Cytosceleton.

Membranbound organelles
Nonmembane organelles
11
Cytoplasm
  • Viscous contents of cell between the nuclear
    membrane and the plasma membrane. This include
    cell organelles
  • Cytosol- aqueous part. The semi-fluid medium
    found in the cytoplasm. This does not include the
    organelles
  • Cytoskeleton nightly organized network fibrous
    proteins that support the cell.

12
Mitochondria
  • A double membrane cellular organelle with its own
    circular DNA (prokaryote like genomes) and
    ribosomes found in both plants and animals.
  • Likely evolved from bacteria that were
    endocytosed (ingested).
  • It is the site of cellular respiration, a
    catabolic, exergonic, oxygen requiring process
    that uses energy extracted from organic
    macromolecules (like glucose) to produce ATP.

13
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14
Endoplasmic reticulum
  • Extensive membranous networks of tubules and sacs
    called cisternae
  • Three distinct regions and maybe more
  • A .Rough Endoplasmic reticulum (RER)
  • Studded with ribosome's. Site of protein
    synthesis.
  • Carbohydrate Addition and modification
  • B. Smooth Endoplasmic reticulum (SER)
  • Synthesizes lipids, phospholipids and steroids.
    Detoxifies drugs, alcohol and poisons
  • Carbohydrate Addition and modification
  • C. Endoplasmic reticulum exit sites
  • Accumulation of proteins (cargos ready for
    export)

15
  • Liver Cell, TEM

16
Ribosomes
  • Nuclear and cytoplasmic organells. Composed of 60
    protein and 40 ribosomal RNA rRNA
  • Site of protein synthesis
  • Can be found or as Polyribosomes

17
Golgy apparatus (complex)
  • Stacked, flattened membranous organelle with sacs
    called cisternae
  • Modifies, stores, and routes products from the ER
    to the Plasma membrane

18
Golgi Body Lysosomes
  •  

19
Transport vesicles
  • A membrane organelle that transits materials from
    one part of the cell to another
  • ER-to Golgy apparatus
  • Golgy apparatus-to ER
  • Golgy apparatus-to PM
  • PM-to Golgy apparatus

20
Lysosomes endosomes
  • Membrane-enclosed bag of hydrolytic enzymes
    (digestive enzymes)
  • Degradation of old cell components or ingested
    materials
  • Low pH (membrane proteins pumps in H )
  • Degradative enzymes (nucleases, proteases)

21
  • Golgi body Peroxisome which is a specialized
    form of lysosome.

22
Vacuoles
  • Large membrane-closed sac for cellular storage
  • Three types
  • Food vacuole (lysosomes attach)
  • Contractile vacuole (Protozoons)
  • Central vacuole (mature plant cell)

23
Plasma membrane
  • The boundary of every cell approximately 8nm
    thick
  • Separates the living cell from its nonliving
    surroundings.
  • Functions
  • Acts as selective barrier
  • Regulate movement of material into and out of the
    cell
  • Cellular recognition

24
Plasma membrane
  • envelops the cell and aids in maintaining its
    structural and functional integrity.
  • Composed of lipid bilayer and associated
    proteins.
  • Membrane proteins may be integral (are dissolved
    in the lipid bilayer) and peripheral proteins
    (dont extend into the lipid bilayer).

25
Plasma membrane
  • Lipid bilayer is composed by phospholipids
    (hydrophilic and hydr?phobic), glycolipids and
    cholesterol.
  • Glycolipids are present in outer leaflet only.
    They have polar carbohydrate residues that extend
    from the outer leaflet into the extracellular
    space, forming part of glycocalix.

26
Plasma membrane
  • Cholesterol is located in both leaflets of the
    plasma membrane. It is constitutes approximately
    2 of the plasmalemma lipids and assists in
    maintaining the structural integrity of the
    plasma membrane.
  • Fluidity of the lipid bilayer is crucial to such
    activities as exocytosis, endocytosis, membrane
    trafficking and membrane biogenesis.

27
CYTOSKELETON
  • Network of fibers through out the cytoplasm.
  • Aids in cellular support and movement.
  • Composed of three components
  • 1. Microfilaments - globular protein (actin)
  • - support and cellular contraction
  • 2. Intermediate filaments - fibrous protein
  • - support
  • 3. Microtubles - globular protein (tubulin)
  • - support and cell motility

28
  • In these cells, actin filaments appear light
    purple, microtubules yellow, and nuclei greenish
    blue. This image, which has been digitally
    colored, won first place in the 2003 Nikon Small
    World Competition. TORSTEN WITTMANN

29
Cytoskeleton
30
CENTRIOLES
  • found in animal cells only
  • Paired cylindrical organelles near nucleus
  • - Composed of nine tubes, each with three
    tubules
  • - Involved in cellular division
  • - Lie at right angles to each other

31
Nucleus
  • The cell nucleus is a conspicuous membrane-bound
    cellular organelle.
  • It functions to
  • Store genes into chromosomes to allow cell
    division
  • Transport regulatory factors and gene products
    vie nuclear pores
  • Produce messages (messenger ribonucleic acid or
    mRNA) that code for proteins
  • Organise the incoiling of DNA to replicate key
    genes

32
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33
Nucleolus
  • Spherical region in nucleus
  • Found in non-dividing cells
  • It is nuclear organizers and synthesize rRNA
  • Sometimes more than one nucleolus present

34
Nuclear envelope
  • Encloses the nucleus
  • A double membrane perforated wit pores through
    which materials enter and leave the nucleus.
  • The pores are octagonal orifices about 60nm in
    diameter forming the pore complex with the annulus

35
Heterochromatin -- tightly packed regions
Euchromatin --- Regions where DNA is more openly
packed, location of most functional genes
Chromosome banding (requires special stains)
36
  • Types of chromosomes

37
Karyotype is a diploid number of chromosomes and
it is a characteristics of the number and
morphology of chromosomes, that is peculiarities
of each species.
  • Male karyotype
  • 4622AXY
  • Female karyotype
  • 4622AXX

38
The cell cycle
  • Covers a time from one division of cells till
    other division or destruction (perish) of cell
  • It has two major stages
  • 1) mitosis
  • 2) interphase

39
Cell Cycle Interphase
  • Before mitosis
  • Time of high metabolic activity
  • DNA replicated and synthesized
  • Three phases G1, S, and G2
  • G1(gap 1)- longest stage of cell cycle, RNA,
    protein sysnthesis
  • S (synthesis)- DNA replicated , 2 chromatids per
    chromosome, chromatids genetically identical
  • G2(gap 2)- RNA synthesis, not well understood

40
The human cell cycle
DNA synthesis synthesis
S
phase
G1
phase
Rapid growth and preparation for DNA synthesis
G2
phase
Growth and preparation for cell division
M
phase
Mitosis
41
Cell Cycle Mitosis
  • Process of cell division(nuclear division) which
    produces daughter cells genetically identical to
    the parent cell
  • Four Phases (P-M-A-T) prophase, metaphase,
    anaphase, and telophase.
  • Upon completion of the phases of mitosis (nuclear
    division) the cell officially divides into two
    by a process called cytokinesis - division of
    cytoplasm

42
Cell Cycle
43
Interphase Not part of mitosis DNA is
replicated chromosomes start to condense
44
Chromosome duplication
45
Prophase Chromosomes coil and condense
further. Nuclear membrane breaks down/
disappears. Microtubules increase in number,
spindle apparatus forms.
46
G2, Prophase
47
Metaphase Nuclear membrane completely
disappeared Chromosomes move to equator of cell
- begin to line up Chromosomes attach to spindle
via kinetochore
48
Centromeric Region
49
Anaphase Movement of chromosomes via
microtubules to opposite sides of the cell.
50
Chromatid Separation
51
  • In anaphase, the sister chromatids separate.
  • Two daughter cells
  • Each has a complete and identical set of
    chromosomes

52
Telophase Genetically identical info at each
pole Spindle fibers disappear Chromosomes
uncoil Nuclear envelope reforms around
53
Metaphase, Anaphase, Telophase
METAPHASE
ANAPHASE
Metaphase plate
Nuclear envelope forming
Spindle
Daughter chromosomes
54
Mitosis in a plant cell
55
Cytokinesis
Cytokinesis - is separate from mitosis,
pinching of cell/divison of cytoplasm.
Mitosis Cytokinesis result in two identical
daughter cells.
56
Mitosis
57
Histologic picture of Mitosis
58
Mitosis
  • Interphase No morphological changes, Replication
    of DNA and organelles.
  • Prophase Visible chromosomes
  • Metaphase equatorial plate formation
  • Anaphase Separation of chromosome pairs
  • Telophase Two separate nuclei formation.
  • Cytokinesis Separation of daughter cells.

59
Chromosomes and Chromatids During Mitosis
Begin Interphase After Interphase After Prophase After Metaphase After Anaphase After telophase
? of Chromosomes 46 46 46 46 92 46
? of Chromatids 46 92 92 92 92 46
60
Cell division
61
Meiosis
  • Cell division which results in haploid sex
    cells (i.e., egg and sperm)
  • One replication of the genetic material (DNA)
    during interphase, but two nuclear divisions
    (meiosis I and meiosis II).
  • Results in haploid (N) cells ( gametes in
    animals) from an initial diploid (2N) cell
  • Very similar to mitosis except that the cells
    produced are not genetically identical.

62
Overview of meiosis how meiosis reduces
chromosome number
63
Meiosis
  • Meiosis I (reduction)
  • Prophase I is divided into the following
    five stages
  • Leptotene -the chromatin condenses into the
    visible chromosomes, each of which contain two
    chromatids joined at the centromere
  • Zygotene - homologous maternal and paternal
    chromosomes pair and make physical contact
    (synapsis), forming a tetrad

64
Prophase I
.
  • Pachytene - the chiasmata are formed and crossing
    over (random exchanging of genes between segments
    of homologous chromosomes) occurs an event that
    is crucial for increasing generic diversity
  • Diplotene - the chromosomes continue to
    condense and chiasmata can be observed,
    indicating where crossing over has taken place
  • Diakinesis - the nucleolus disappears,
    chromosomes are condensed maximally, and the
    nuclear envelope disappears

65
Metaphase I
  • Spindle formation is complete
  • Bivalents are aligned at equator
  • Kinetochore microtubules of the homologues point
    to opposite poles
  • Anaphase I
  • Homologues separate and move toward opposite
    poles
  • Cytokinesis begins

66
The stages of meiotic cell division Meiosis I
67
Telophase I
  • Spindle dissolves
  • Nuclear envelopes reform
  • Daughter nuclei are haploid
  • Each chromosome is still duplicated
  • Cytokinesis results in 2 daughter cells

68
Meiosis II
  • Equatorial division - begins soon after
    the completion of meiosis I, following a very
    brief interphase without DNA replication.
  • Prophase II
  • chromosomes are still duplicated
  • spindle formation begins
  • nuclear envelope fragments

69
  • Metaphase II
  • Spindle formation is complete
  • Duplicated chromosomes are aligned at equator
  • Kinetochore microtubules of sister chromatids
    point to opposite poles
  • Anaphase II
  • Centromeres divide
  • Haploid sets of chromosomes move toward poles
  • Cytokinesis begins

70
Telophase II
  • Spindle dissolves
  • Nuclear envelopes reform
  • Daughter nuclei are haploid and genetically
    dissimilar from parent cell and each other
  • Cytokinesis results in 4 daughter cells

71
The stages of meiotic cell division Meiosis II
72
Independent Assortment
73
The biological significance of meiosis
  • meiosis enables a species chromosome number to
    remain constant over generation.
  • Meiosis produces novel combination of genes.
  • Meiosis produces novel combination of non
    homologies chromosomes

74
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75
  • Thank you for attention!
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