the study of the cell cell: the smallest unit that can carry on all of life’s processes
TRANSCRIPT
The Study of the cellCell: the smallest unit that can carry on all of life’s processes
CELL THEORY
A theory resulting from many scientists’ observations & conclusions
CELL THEORY 2. All living things are made of 1 or more cells.
Matthias Schleiden (botanist studying plants)
Theodore Schwann (zoologist studying animals) stated that all living things were made of cells
Schleiden
Schwann
CELL THEORY 3. All cells divide & come from old cells. (Virchow)
Virchow
Body Tube
Nose Piece
ObjectiveLenses
Stage Clips
Diaphragm
Light Source
Ocular Lens
Arm
Stage
Coarse Adj.
Fine Adjustment
Base
Skip to Magnification Section
Magnification
To determine your magnification…you just multiply the ocular lens by the objective lens
Ocular 10x Objective 40x:10 x 40 = 400
Objective Lens have their magnificationwritten on them.
Ocular lenses usually magnifies by 10x
So the object is 400 times “larger”
TOTAL MAGNIFICATION Powers of the eyepiece (10X) multiplied by objective
lenses determine total magnification.
Using a Microscope
Start on the lowest magnification Don’t use the coarse adjustment knob on high
magnification…you’ll break the slide!!! Place slide on stage and lock clips Adjust light source (if it’s a mirror…don’t
stand in front of it!) Use fine adjustment to focus
FROM CELL TO ORGANISM
CellThe basic unit of life
TissueGroup of cells working together
OrganGroup of tissues working together
OrganismAny living thing made of 1 or more cells
Organ SystemGroup of organs working together
Eukaryotic Cellhttp://www-class.unl.edu/bios201a/spring97/group6/eukcell.jpg
Parts of Eukaryotic Cells
Endoplasmic Reticulum
Nucleolus
Cytoplasm
DNA
Mitochondria
Vesicles
Golgi Complex
Ribosomes
Nucleus
Cell Membrane
- Parts of Eukaryotic Cells
CELL MEMBRANE (Plasma membrane)
Outer covering, protective layer around ALL cells
Allows food, oxygen, & water into the cell & waste products out of the cell.
CELL MEMBRANE (Plasma membrane)
The boundary of the cell…separates inside from outside of cell
Is Semipermeable Membrane: allows some substances into cell and keeps others out of cell.
CELL MEMBRANE (Plasma membrane)
Has a phospholipid bilayer. The lipid molecules are fluid and can move past one another in a fluid manner…also allows proteins to move and change in this layer thus scientist explain cell membrane and call it a Fluid Mosaic Model
Cell Membrane are made of a phospholipid bilayer
A Phospholipid BilayerPhospholipids can form:
BILAYERS
-2 layers of phospholipids with hydrophobic tails protected inside
by the hydrophilic heads.
The PHOSPHOLIPIDBILAYER is the basicstructure of membranes.
NUCLEUS Directs all cell activities Contains instructions for
everything the cell does These instructions are
found on a hereditary material called DNA
Usually the largest organelle
Parts of the nucleus
Nuclear envelope Nuceolus Nucleoplasm chromosomes
Actual Cell Nucleus
NUCLEOLUS
Aka “little nucleus” Found in the nucleus Contains RNA and
proteins for ribosome synthesis
CHROMATIN
contains genetic code that controls cell made of DNA & proteins Condenses to form chromosomes
during cell division
Made of DNA and proteins
Parts include: 2 sister chromatids
held together by the centrally
located centromere
Cytoplasm
gelatin-like inside cell membrane constantly flows aka protoplasm It contains the various
organelles of the cell
Contains the various organelles
Internal Organization:
Organelles = perform specific functions.- function like tiny organs, analogous to organs of a multicellular body.
Centrioles
Short cylinder near nuclear envelope There generally are 2 at right angles to
each other They control cell division
ENDOPLASMIC RETICULUM A series of folded
membranes that move materials (proteins) around in a cell like a conveyor belt
Smooth ER – ribosomes not attached to ER, functions in lipid synthesis
Rough ER – ribosomes attached to ER, functions in producing proteins
RIBOSOMES
Make proteins Float freely or attached to
the endoplasmic reticulum (ER)
Ribosomes are made in the nucleolus and are small particles of RNA
GOLGI BODIES (GAWL jee)
Stacked flattened membranes
Sort and package proteins
LYSOSOMES (LI suh sohmz)
The word "lysosome" is Latin for "kill body." The purpose of the lysosome is to digest things.
They might be used to digest food or break down the cell when it dies.
Break down food molecules, cell wastes & worn out cell parts
MITOCHONDRIA Organelles that release
energy from food (power house of cell)
This energy is released by breaking down food into carbon dioxide
the powerhouse b/c they release energy (ATP) from food
Folds of mitochodria are called:
VACUOLES
Temporary storage spaces
Store food, water, waste
CYTOSKELETON
scaffolding-like structure in cytoplasm that gives cell its shape
helps the cell maintain or change its shape
made of protein microfilaments and microtubules
Microfilaments
Built from actin, a globular protein and function in support of cytoskeleton and localized contraction of cell
Microtubules
Found in cytoplasm of all eukaryotic cells and function in cell support
Microbodies
Various membrane bound organelles that contain specialized teams of enzymes for specific metabolic pathways
important types: 1. peroxisomes: break down H2O2 and
detoxify alcohol
Intermediate filaments
Size intermediate to microtubules and microfilaments.
Function in reinforcing cell shape
Cilia
Short hair like projections from the cell that by beating produce organized movement.
Found in the trachea
FlagellaLong whiplike organelle
whose action produces movement.
Extracellular material
Found outside cell
Material secreted by cell into the cell matrix, ranging from saliva, to gastric juices, ext…
Transport through cell membranes There are 5 basic mechanisms:
1. DIFFUSION
2. OSMOSIS
3. ACTIVE TRANSPORT
4. FILTRATION
5. ENDOCYTOSIS
Diffusion is the net movement of molecules (or ions) from a region of their high concentration to a region of their lower concentration.
The molecules move down a concentration gradient.
Ex oxygen diffuses from RBC to cells body
Osmosis = Water diffusion, moving “down” the gradient
The net direction of osmosis depends on the solute concentrations on both sides.
Hypotonic = lower solute concentration
Hypertonic = higher solute concentration Isotonic = equal concentrations on both
sides of the membrane
Osmosis in Red Blood Cells
Active Transport
requires energy use to move materials up their concentration
Moves from an area of low concentration to an area of high concentration
Example: sodium-potassium pump Ex nerve cells transport sodium ions to
extracellular environment
Ion Pump for Na+ and K +
process by which cells ingest external fluid, macromolecules, and large particles, including other cells
Two Types of Endocytosis
- Pinocytosis = Cell drinking
- Phagocytosis = Cell eating
Exocytosis of Vesicle Contents
Filtration
Molecules pass through a membrane by physical force during filtration
Ex blood pressure forces substances to leave circulation
The process by which cells reproduce themselves.
Two types (Mitosis and Meiosis)
I. Mitosis = produces body cells with identical genetic material as the original.
II. Meiosis = reduces the chromosome number by half in the sex cells. (haploid)
Chromosomes – composed of 2 sister chromatids connected by centromere
During cell division in eukarotic cells the DNA is coiled into very compact chromosomes, made of both DNA and proteins.
Chromatid – each chromosome consists of two identical halves called chromatids (= copies
Chromatin - Before cell division, the DNA is not tightly coiled, but loosely arranged, and its codes can then be read by the cell to direct the cell’s activities.
chromosome
centromere
chromatids
Homologues or homologous chromosomes
* The cycle = repeating set of events composing the life of a cell.* There are two periods: Interphase and Cell Division
Interphase is the time between divisions, and is divided into three phases.
1. G1 phase – offspring cells grow to mature size
(= Gap after division and before DNA replication)
2. S phase – The DNA is copied 3. G2 phase – Gap after DNA synthesis &
before division.(The cell is preparing for division.)
* Cells can exit the G1cell cycle at G1 and enter a
state called Go phase. (In G0 , nerve cells for example stop dividing.)
Chromosomes duplicateChromosomes are not
visibleNucleus has clearly defined
nucleus
LOOKS SPAGHETTI LIKE, longest phase
The DNA which was copied in S phase, now supercoils.
Nucleolus and nuclear membrane break down.
Centrosomes with centrioles move to poles. (Plants have no centrioles.)
Spindle fibers (microtubules) radiate from them.
Mitotic spindle is this array of fibers.
Metaphase – CHROMOSOMES line up in a straight line in the center ( equatorial plane) of the cell .
Centromere of each pair of chromatids attaches to a separate spindle fiber.
Anaphase – centromeres & chromatids separate.
(Each new chromosome moves slowly to opposite poles
Shortest phaseLooks like they have wiped out
waters skiing
Plant Anaphase 3-D
Telophase – spindle fibers disassemble, chromatin forms, nucleus reappears.
(new nuclear envelope forms for each set of chromosomes
Cell plate forms in plant cell Cleavage furrows appear in animal
cells
Mitosis
Telophase Metaphase Prophase Anaphase
Cell Division Puzzle: Mitosis Unscramble it by labeling & numbering the stages.
Metaphase (second) Cytokinesis (fifth) Prophase (first)
Telophase (fourth) Interphase (sixth) Anaphase (third)
Meiosis is a process in which gonad cells divide twice to produce haploid cells.
* Gonads are sex organs (ovaries and testicles).
* Gametes (sex cells – sperm and eggs) are the resulting haploid cells.
* Cells preparing for meiosis first undergo the G1, S, and G2 phases of interphase.
Meiosis I and Meiosis II are the names for the two divisions of Meiosis. There are some important differences in
the stages compared to mitosis.
Exploring Meiosis
Meiosis I – Has four stages, plus Cytokinesis(Prophase I, Metaphase I, Anaphase I, Telophase I)
*
Similar to mitotic prophase except for Synapsis.
Synapsis is where the homologues pair up & twist around one another.
Tetrads is the term for these paired homologues (4 chromatids).
Crossing-Over then occurs where parts of the chromatids exchange genes.
Genetic Recombination is the result, which increases variation.
tetrads line up randomly at the mid-line of cell
- Spindle fibers from one pole attach to one centromere of one homologue.
- Spindle fibers from the other pole attach to the other homologue’s centromere.
* the spindle fibers randomly pull the homologues to separate poles.
- Independent Assortment is the term for the random separation.
- Note that the centromeres do not split the chromatids at this point.
- The homologous chromosome (consisting of two chromatids) stays intact.
Telophase I – is the final phase of Meiosis I, and the chromosomes reach the poles.
Cytokinesis then begins to separate the cytoplasm into TWO new cells.
At this point, the TWO new cells contain a Haploid number of chromosomes, yet each has two sister chromatids (copies) attached by a centromere.
Meiosis II - the DNA is NOT duplicated in meiosis II.
* Prophase II – spindle fibers form and begin moving chromosomes to midline.
* Metaphase II – chromosomes are at the midline, facing the poles.
* Anaphase II – chromatids separate at the centromeres and move to opposite poles.
* Telophase II & Cytokinesis results in four haploid cells, each with a single chromatid.
Formation of Gametes-
* Spermatogenesis = male testes cell produces four gametes called spermatids.
* Oogenesis = female ovaries produce eggs (ova), but only one ova (not four) is produced from the meiotic divisions of each ovary cell.
- The other three “donate” most of their cytoplasm to the one mature ova, so that it has plenty of
energy reserves to grow once it is fertilized by a sperm.
Cell Growth and Reproduction
DNA transcription to RNA Translation to protein
DNA contains the genetic info for making proteins
Cells make protein by translating the genetic codes into protein
So DNA controls life by controlling protein synthesis
Replication: DNA copies itself
Transcription: DNA copies to mRNA Translation: mRNA copies to tRNA to protein
3 Types of RNA: mRNA: found in the cytoplasm and specifies the
exact sequence of amino acid tRNA: acts as an interpreter molecule which
recognize specific amino acids and nucleotide base sequences
rRNA: forms part of the protein synthesis site in the cytoplasm
Synthetase enzymes: attach the correct amino acids to its transfer RNA