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CYTOLOGY

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CYTOLOGY THE STUDY OF CELLS - FUNCTION CELLULAR ACTIVITIES Transport systems Processes of Transport Across Cell Membrane The Cell Cycle Cellular Activities ... – PowerPoint PPT presentation

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Title: CYTOLOGY


1
CYTOLOGY
  • THE STUDY OF CELLS - FUNCTION

2
CELLULAR ACTIVITIES
  • Transport systems Processes of Transport Across
    Cell Membrane
  • The Cell Cycle Cellular Activities from
    Formation to Death or Division
  • Protein Synthesis using DNA RNA to make
    proteins

3
TRANSPORT SYSTEMS
  • Passive Transport (does not require energy)
  • Active transport (does require energy ATP most
    common form)

4
PASSIVE TRANSPORT SYSTEMS
  • Diffusion
  • Facilitated diffusion
  • Osmosis

5
PASSIVE TRANSPORT SYSTEMS DIFFUSION
  • Molecules in constant motion
  • Molecules move from high to low
  • Continues until Equilibrium

6
DIFFUSION
7
Diffusion through a membrane
8
FACILITATED TRANSPORT OR DIFFUSION
  • Requires special proteins (enzymes)
  • Integral Membrane Proteins
  • Escort molecules across membranes (e.g. Glucose)

9
Facilitated Diffusion
10
OSMOSIS
  • Special case of diffusion
  • Only water moves
  • Water moves across a selectively permeable
    membrane
  • Water moves from low solute to high solute

11
OSMOSIS
12
Tonicity
  • Concentration of solutes in a solution (relative
    to the concentration inside the cell)
  • Isotonic concentration is the same
  • Hypotonic lower concentration of solutes
  • Hypertonic higher concentration of solutes

13
TONICITY
14
ACTIVE TRANSPORT SYSTEMS
  • Facilitated active transport
  • Endocytosis
  • Exocytosis

15
FACILITATED ACTIVE TRANSPORT
  • Molecules are moved against a concentration
    gradient
  • Integral Proteins act as Carrier Molecules
  • Sodium and potassium pump moves Na out of cell
    and K into cell

16
Active Transport
17
ENDOCYTOSIS
  • Materials accumulate at surface of plasma
    membrane
  • Membrane evaginates or invaginates, pinches off
  • Includes
  • phagocytosis engulfment of large solids (e.g.
    WBCs bacteria/viruses)
  • pinocytosis engulfment of extracellular fluid

18
EXOCYTOSIS
  • Releases substances outside cell
  • Secretory vesicles fuse to cell membrane
  • Cellular products, e.g., secretion
  • Cellular wastes

19
Endocytosis Exocytosis
20
CELL CYCLE
  • Interphase
  • Cell Division
  • Mitosis
  • Cytokinesis

21
CELL CYCLE INTERPHASE
  • High metabolic activity
  • Protein synthesis
  • DNA replication (46 ? 92)

22
CELL CYCLE MITOSIS
  • Growth Repair
  • 4 phases
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase

23
MITOSIS PROPHASE
  • Chromatin condenses into chromosomes
  • Centrioles organize spindle
  • Spindle fibers attach to centromeres
  • Nuclear membrane disassembles
  • Nucleolus disassembles

24
MITOSIS METAPHASE
  • Spindle aligns
    chromosomes
  • Alignment is around equator
  • Alignment is random

25
MITOSIS ANAPHASE
  • Daughter chromosomes separate
  • Chromosomes are moved toward poles
  • Cytoplasm elongates cytokinesis begins

26
MITOSIS TELOPHASE
  • Reverse of prophase
  • Chromosomes relax into chromatin
  • Nuclear membrane reassembles
  • Nucleolus reassembles

27
CELL CYCLE CYTOKINESIS
  • Division of the cytoplasm and organelles
  • Begins during anaphase
  • Completed following telophase

28
Mitosis
29
CYTOLOGY
  • PROTEIN SYNTHESIS

30
PROTEIN SYNTHESIS
  • Involves DNA RNA
  • DNA codes for proteins
  • RNA assembles proteins
  • Gene a segment of DNA that codes for one
    protein
  • The sequence of bases (nucleotides) carries the
    information

31
Protein Synthesis cont.
  • T, A, C, G in DNA
  • U, A, C, G in RNA
  • A single gene has between 300 3000 base pairs
  • In DNA, each 3-base sequence (triplet) specifies
    one amino acid

32
PROTEIN SYNTHESIS
  • Each strand of DNA is complementary to the other
  • Messenger RNA is complementary to DNA carries
    instructions from DNA to ribosomes
  • Protein synthesis occurs at ribosomes

33
RIBONUCLEIC ACID (RNA)
  • Messenger RNA (mRNA)
  • polynucleotide strand that is complementary to
    DNA
  • carries instructions from DNA to ribosomes
  • Transfer RNA (tRNA) transports amino acids to
    ribosomes
  • Ribosomal RNA (rRNA) part of ribosomes

34
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35
DNA Replication
36
PHASES OF PROTEIN SYNTHESIS
  • Transcription
  • Complementary mRNA is made from a DNA gene
    (sequence coding for a protein)
  • Translation
  • mRNAs information is used to assemble proteins
    with the help of tRNA rRNA

37
Overview of Protein Synthesis
38
TRANSCRIPTION
  • Occurs in nucleus
  • DNA strands uncoil separate
  • Triplet 3-base sequence specifying an amino
    acid (DNA)
  • Codon complementary 3-base sequence in mRNA
  • E.g. DNAATA-GTA-CCC-GTA
    RNAUAU-CAU-GGG-CAU

39
Transcription
40
TRANSLATION
  • Occurs in cytoplasm
  • mRNA enters cytoplasm attaches to ribosome
  • Anticodon 3-base sequence in tRNA that is
    complementary to mRNAs codon
  • tRNA brings amino acid binds to complementary
    codon on mRNA
  • Each tRNA is specific for an amino acid

41
Translation
42
TRANSLATION continued
  • Ribosome moves along mRNA
  • Amino acids from adjacent tRNAs are joined by
    peptide bonds
  • tRNA is released as its amino acid is added to
    the growing polypeptide
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