CYTOLOGY THE STUDY OF CELLS - FUNCTION Slide 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
Slide 3 TRANSPORT SYSTEMS Passive Transport (does not require
energy) Active transport (does require energy; ATP most common
form) Slide 4 PASSIVE TRANSPORT SYSTEMS Diffusion Facilitated
diffusion Osmosis Slide 5 PASSIVE TRANSPORT SYSTEMS: DIFFUSION
Molecules in constant motion Molecules move from [high] to [low]
Continues until Equilibrium Slide 6 DIFFUSION Slide 7 Diffusion
through a membrane Slide 8 FACILITATED TRANSPORT OR DIFFUSION
Requires special proteins (enzymes) Integral Membrane Proteins
Escort molecules across membranes (e.g. Glucose) Slide 9
Facilitated Diffusion Slide 10 OSMOSIS Special case of diffusion
Only water moves Water moves across a selectively permeable
membrane Water moves from [low solute] to [high solute] Slide 11
OSMOSIS Slide 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 Slide 13
TONICITY Slide 14 ACTIVE TRANSPORT SYSTEMS Facilitated active
transport Endocytosis Exocytosis Slide 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 Slide 16 Active
Transport Slide 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 Slide 18 EXOCYTOSIS Releases substances outside cell
Secretory vesicles fuse to cell membrane Cellular products, e.g.,
secretion Cellular wastes Slide 19 Endocytosis Exocytosis Slide 20
CELL CYCLE Interphase Cell Division -Mitosis -Cytokinesis Slide 21
CELL CYCLE: INTERPHASE *High metabolic activity *Protein synthesis
*DNA replication (46 92) Slide 22 CELL CYCLE: MITOSIS Growth &
Repair 4 phases: -Prophase -Metaphase -Anaphase -Telophase Slide 23
MITOSIS: PROPHASE Chromatin condenses into chromosomes Centrioles
organize spindle Spindle fibers attach to centromeres Nuclear
membrane disassembles Nucleolus disassembles Slide 24 MITOSIS:
METAPHASE Spindle aligns chromosomes Alignment is around equator
Alignment is random Slide 25 MITOSIS: ANAPHASE Daughter chromosomes
separate Chromosomes are moved toward poles Cytoplasm elongates
& cytokinesis begins Slide 26 MITOSIS: TELOPHASE Reverse of
prophase Chromosomes relax into chromatin Nuclear membrane
reassembles Nucleolus reassembles Slide 27 CELL CYCLE: CYTOKINESIS
*Division of the cytoplasm and organelles *Begins during anaphase
*Completed following telophase Slide 28 Mitosis Slide 29 CYTOLOGY
PROTEIN SYNTHESIS Slide 30 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 Slide 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 Slide
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 Slide 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
Slide 34 The preview Image has been scaled down to fit the screen.
Actual image is both larger and clearer. Slide 35 DNA Replication
Slide 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 Slide 37 Overview of Protein Synthesis
Slide 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.
DNA:ATA-GTA-CCC-GTA RNA:UAU-CAU-GGG-CAU Slide 39 Transcription
Slide 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 Slide 41 Translation Slide 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
