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

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

 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***

 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

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]

 isotonic – a solution that neither gains or loses H 2 O, has the same concentration of solutes as the solution with which it is being compared  hypertonic – a solution that gains H 2 O because it has a higher concentration of solutes than the solution with which it is being compared  hypotonic – a solution that loses H 2 O because it has a lower concentration of solutes than the solution with which it is being compared

 blood pressure causes filtration of H 2 O & dissolved substances through porous capillary walls  urine formation – nephrons of kidney

 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

 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)

 DNA – double helix, sugar is deoxyribose adenine (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

 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

 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