Cytology

Study of cells~70 trillion = human body

Cells

• Cells vary greatly in SIZE and STRUCTURE• two main parts - NUCLEUS & CYTOPLASM,

Enclosed in a CELL MEMBRANE (also called PLASMA MEMBRANE)

Cell Membrane

• Extremely thin• Outpouchings and infoldings• Porous• Selectively Permeable = controls what enters

and leaves the cell, it allows some things to pass but not others

Membrane Structure

• Lipids, proteins, carbs• Phospholipid bilayer

• CYTOPLASM - area b/w the plasma membrane and nucleus. – metabolic reactions/activities take place.

• Filled with a clear fluid called CYTOSOL. • Contains ORGANELLES

• Cytoskeleton- – protein rods/ tubules

• Microfilaments- tiny rods of the protein actin– Various cell movements

• Microtubules- long slender tubes of globular protein tubulin. – Maintain shape of cell– move organelles in cell

Organelles

• Ribosome-– Protein/RNA– Structural support– Link amino acids together to form proteins

• Endoplasmic Reticulum-– Smooth ER- • contains enzymes that synthesize lipids, absorb fats

from digestive tract, break down drugs.

– Rough ER- Contains Ribosome• Site of Protein Synthesis• Send to Golgi Apparatus

• Golgi Apparatus- – proteins arrive in vesicles from ER– Modifies proteins chemically– Send proteins in vesicles out of cell (vesicle

trafficking)

• Vesicles- membranous sacs that vary in size/contents

• Mitochondria- 2 layers of membranes– Cristae- folded inner membrane– Matrix- fluid inside membranes– Captures/Transfers energy in the form of ATP

• Lysosome- – acts as garbage disposal– Break down proteins, carbs, nucleic acids– Destroy worn cell parts

• Peroxisomes- contain enzymes– Catalyze chemical reactions• Synthesis of bile acids• Breakdown of lipids• Degradation of rare biochemicals• Detoxification of alcohol

• Centrosome- two hollow cylinders (centrioles)– Made of microtubules– From spindle fibers to move chromosomes during

mitosis

• Cilia/Flagella- • motile extensions of certain cells

Nucleus

• Spherical structure • Contains DNA

• Nuclear Envelop- double layered membrane• Nuclear pores- allow substances in and out• Nucleoplasm- fluid inside• Nucleolus- Site of ribosome production– Ribosomes move out nuclear pores

• Chromatin- DNA fibers – Form chromosomes in mitosis

MEMBRANES

• phospholipid bilayer• 2 Tails- Hydrophobic • Head- Hydrophilic • Controls movement of substances in and out of cell

• Peripheral proteins• Integral proteins• Function– Help communicate with other cells– Transport substances across membrane

• Subs move throughout membrane

Passive Transport

• Diffusion- movement of particles from a concentrated area to a less concentrated area

• Equilibrium

Diffusion Example

Diffusion

Passive Transport

• Osmosis- transport of water across membrane from a high concentration to a lower concentration– Hypertonic– Hypotonic– Isotonic

Passive Transport

Facilitated Diffusion- Transport proteins = pathway for molecules to

pass through membrane

Active Transport

• Uses Energy• Moves against concentration gradient• Some Carrier proteins act as pumps

• Sodium Potassium Pump– Na+ binds to carrier protein inside cell– Carrier protein splits Phosphate group from

molecule of ATP and phosphate group binds• ATP supplies energy needed to reshape protein

– With new shape moves Na+ outside cell, and the shape is perfect to bind for K+

– Repeats

Active Transport

• Exocytosis- vesicles exports product from cells

• Endocytosis- vesicle takes material into cell– Pinocytosis- transports of solutes or fluids– Phagocytosis-movement of large particles or whole cells

Cell Life Cycle

• Mitosis = nuclear division• followed by cytokinesis • The steps of mitosis ensure that each new cell

has the exact same number of chromosomes as the original

• Interphase– 90% of cells life– G1 – growth phase– S phase (synthesis) – genetic material replicates– G2 – synthesize structures

Mitosis

Prophase

• 1. chromosomes visible (chromatids)• 2. centrioles migrate to the poles• 3. nuclear membrane disappears• 4. nucleolus disappears• 5. spindle forms

Metaphase

• chromosomes line up on the equator, spindle attaches

Anaphase

• chromatids separate and move to opposite poles

Telophase

• 1. chromosomes disappear • chromatin• 2. nuclear membrane reforms• 3. nucleoli reappears• 4. spindle disappears• 5. centrioles duplicate

Cytokinesis

• division of the cytoplasm to form 2 new daughter cells

• - organelles are divided• - daughter cells are genetically identical

Karyotype

Homework

• Draw and label the phases of mitosis• Label : Centromere, centrioles, spindle fibers,

and sister chromatids