A&P: Cell & Mitosis, Models, Mitosis Plaque, Experiments on Cell Processes

Lab 1 slides

Cell

Structural and functional unit of all living things; maintain boundaries, and perform metabolic functions (three major parts: nucleus, plasma membrane, cytoplasm).

Nucleus

Contains genetic material

• Chromatin: loose threadlike DNA

• Chromosomes: condensed DNA

• Nucleoli: protein

• RNA: factories of ribosomal particles

• Nuclear membrane: double layered and encloses nucleus; large pores allow RNA to exit

Plasma membrane

Boundary between inside and outside of the cell; made of a phospholipid bi-layer with proteins and potentially cholesterol and glycolipids/glycoproteins embedded

Cytoplasm

Found between plasma membrane and nucleus; cytosol is the fluid-like material that holds organelles and other cellular constituents

Ribosome

Site of protein synthesis and assembly; consists of RNA and protein

Endoplasmic reticulum (E.R.)

Tubular system for transport of cellular substances with two types:

• Rough E.R. is studded with ribosomes which produce proteins for export out of cell

• Smooth E.R. has no ribosomes, is a steroid-based hormone producer

Golgi apparatus

Flattened sacs that modify and package proteins

Lysosomes

Membrane bound sacs containing digestive enzymes that eliminate worn out cell structures and foreign substances

Peroxisomes

Vesicles which contain peroxide and help detoxify substances that enter the cell

Mitochondria

Site of ATP production

Cytoskeletal elements

Form internal scaffolding called the cytoskeleton

Microtubules

Produce parts of the spindle

Intermediate filaments

Help resist pulling forces on the cell

Microfilaments

Allow for cell movement and plasma membrane stability

Centrioles

Involved in direct formation of spindle, basis for cilia or flagella

Inclusions

Areas where substances are found suspended in the cytosol

Mitosis

Nuclear division

Cytokinesis

Cell/cytoplasm division

Interphase: normal cell cycle where cell grows and performs metabolic activity

• G₁: growth following previous cell division

• S: synthesis of DNA for mitosis

• G₂: final preparation for division

• M: Mitosis

Prophase: chromatin condenses into chromosomes, nuclear envelop disintegrates, chromosomes move to opposite ends of cell

Metaphase: chromosomes line up at equator of cell, enzymes split sister chromatids from each other

Anaphase: sister chromatids are pulled to each pole, cytokinesis starts with formation of a cleavage furrow

Telephase: chromosomes uncoil back into chromatin, nuclear envelope is reformed, cytokinesis continues

Passive transport

• Cell does not need to provide energy

• Driving force is concentration or pressure difference

• Two passive processes: diffusion, filtration

Types of passive processes

• Simple diffusion

• Osmosis

• Facilitated diffusion

Tonicity

Ability of a solution to change the shape of a cell immersed in it due to changes in the cell’s water volume; three types: isotonic, hypotonic, hypertonic

Hemolysis

Bursting of red blood cells due to excessive osmotic pressure from within

Crenation

Shrinking of cells due to loss of water

Filtrate

What is allowed to pass through filter

Retentate

What is kept from passing through the filter

Active transport

• Drive directly by ATP

• Requires carrier proteins (solute pump)

• Independent of concentration gradients

Types of active processes

• Active transport

• Vesicular transport: material moves into/out of cell in membranous vesicles

Endocytosis

Movement into cell; three types: pinocytosis, phagocytosis, receptor mediated endocytosis

Exocytosis

Ejection of materials from the cell

Pinocytosis (fluid-phase endocytosis): engulfment process that uses ATP; plasma membrane sinks into the cell trapping particles which end up inside a pinocytic vesicle inside the cell

Phargocytosis: engulfment process that uses ATP; plasma membrane expands and surrounds a substance forming a phagosome (a vesicle)

Receptor-mediated endocytosis: uses plasma membrane receptors to selectively bind to specific molecules (ligand); allows their passage via specialized vesicle