CELLS & TISSUES Chapter 3 – Pgs. 42-59

CELLS & TISSUESChapter 3 – Pgs. 42-59

Cells vary in size, shape, and function; the shape is closely related to function

Composition of CellNucleus, Cytoplasm, Cell Mebrane

Cytoplasmic organelles perform specific function, but the nucleus controls the overall activities of the cell

Cell Membrane (fluid mosaic)Fig. 3-1

forms outermost boundary selectively permeable – controls

movement of substances into and out of cells

mainly phospholipids but also includes proteins, & carbohydrates

molecules lipid soluble will pass easily; barrier to water soluble substances

proteins function as receptors or form channels

Cytoplasm is the area between nucleus and cell membrane, contains organelles – Fig. 3-2, Table 3-1, ***Know functions of each organelle***

Nucleus Enclosed in double layered (pores)

nuclear envelope that controls the movement of substances between the nucleus& cytoplasm

Nucleolus is a dense body of protein & RNA that functions in the production of ribosomes

Chromatin is composed of loosely coiled fibers of protein and DNA that condenses into the structures known as chromosomes during cell division

Movements through cell membranes

Passive transport – no energy required, substances move from an area of high concentration to low concentration (concentration gradient) – Fig. 3-2 diffusion

- scattering of molecules or ions from high concentration to low concentration

- responsible for the exchange of oxygen and carbon dioxide within the body

- rate of diffusion can be increased by short distance, high concentration of diffusion molecules, low molecular weight, & high temperature

facilitated diffusion – carrier molecules (usually proteins) transport a substance from [high] to [low]

 Osmosis – H2O molecules move from [high] to [low] through a

selectively permeable membrane – (Clinical Application pg. 54)

isotonic – a solution that neither gains or loses H2O, has the same concentration of solutes as the solution with which it is being compared

hypertonic – a solution that gains H2O because it has a higher concentration of solutes than the solution with which it is being compared

hypotonic – a solution that loses H2O because it has a lower concentration of solutes than the solution with which it is being compared

Filtration – forced – movement of molecules from regions of higher hydrostatic pressure to lower hydrostatic pressure

blood pressure causes filtration of H2O & dissolved substances through porous capillary walls

urine formation – nephrons of kidney

Filtration

Active Transport – requires energy (ATP) and involves the action of carrier molecules in the cell membrane; moves substance “up the concentration gradient”; from [low] to [high] – Table 3-3

Active Transport – requires energy (ATP) and involves the action of carrier molecules in the cell membrane; moves substance “up the concentration gradient”; from [low] to [high] – Table 3-3 Permease (pump systems) – protein

driven transport systems – Fig. 3-4 Endocytosis – cells take in large

molecules from their surrounding Phagocytosis – large molecules, ex. – white

blood cell engulfing bacteria Pinocytosis – water and small molecules

Exocytosis – cells release materials

Sodium Potassium Pump

Cell Reproduction & Heredity

Mitosis – a parent cell divides once to produce two genetically identical daughter cells; daughter cells contain the same number of chromosomes as the parent cell; both are diploid in chromosome number (2n)

Meiosis – a parent cell divides twice to produce four cells (gametes) that contain a haploid (n) number of chromosomes; “male” & “female” gametes fuse at fertilization to produce a zygote (2n)

Mitosis

Meiosis

DNA & RNA carry genetic information

DNA – double helix, sugar is deoxyriboseadenine (purine) – thymine

(pyrimadine)guanine(purine) – cytosine

(pyrimadine)

RNA – Single stranded, sugar is ribose, uracil (pyrimadine) replaces thymine

Gene – a segment of a chromosome that is made up of specific base pairs and codes for proteins

Protein Synthesis transcription – synthesis of RNA using a DNA template

translation – the assembly of amino acids to form a polypeptide chain, in a sequence specified by the order of nucleotide in a molecule of mRNA

Cell Cycle – Interphase and Mitotic Phase (mitosis & cytokinesis) – Fig. 3-6

Interphase – cell grows and “does its specific job”, chromosomes are replicated (duplicated) during this phase

Mitosis – division of the chromosomes – Table 3-5 **Know**

Cytokinesis – division of the cytoplasm

MITO

SIS