b Rod shaped structure Made of a single DNA molecule and proteins called histones –Histones maintain shape of chromosomes –Aids in tight packing of DNA Seen during cell division Coiled and compact

DNA and Chromosomes double-stranded DNA molecule

centromere homologous chromosomes

DNA Replication

b Chromosome consists of two identical halves Each half is a chromatid –Formed when DNA makes a copy of itself before cell division –Each new cell will receive one chromatid from each chromosome –Chromatids are held together by a centromere

sister chromatids DNA replication

23 pairs Sex chromosomes autosomes

Interphase- 75% of cell life cycle G 1 : rapid growth S: DNA replicates; centrioles replicate. G 2 : cell prepares for cell division; microtubular structures form.

Cell Division Mitosis: cell divides its nuclear components (chromosomes). Cytokinesis: cell divides its cytoplasmic components.

Prophase Metaphase Anaphase Telophase

centrioles chromatin plasma membrane nucleolus nuclear envelope

lChromosomes shorten and become visible (early prophase) lChromosomes made up of 2 identical chromatin threads called chromatids lCentrioles migrate toward opposite pole pulled by kinetochore lNuclear envelope disintegrates (late prophase).

centromere chromosome aster centrioles

aster polar fiber chromosomal fiber fragmenting nuclear envelope

centrioles nucleus

lChromosomes lined up in the middle lMitotic spindle complete.

metaphase plate spindle

polar fiberschromosomal fibers sister chromatids

Chromosome at Metaphase

lSister chromatids (= identical strands of DNA) split from each other to form divided identical chromosomes. lKinetochore fibers shorten and pull divided identical chromosomes to opposite sides of the dividing cell. lPolar microtubules slide past each other, lengthening and pushing the cell apart

daughter chromosomes

lDivided chromosomes reach opposite sides of cell and begin to disperse as chromatin. lNuclear envelopes reforms around separated collections of chromosomes to form two nuclei. lCytokinesis- completion of cell division

lSpindle apparatus disintegrates. lCytokinesis usually begins near the end of telophase.

lSeparation of cytoplasmic components to yield two daughter cells lMicrofilaments form a contracting ring that pinches the plasma membrane inward between the forming daughter cells

cleavage furrow

RNA

Contrasting RNA with DNA lSingle-stranded lRibose lBases Adenine Uracil Guanine Cytosine lDouble- stranded lDeoxyribose lBases Adenine Thymine Guanine Cytosine RNA DNA

mRNA- copies DNA and directs protein synthesis rRNA- joins with ribosomal proteins to make ribosomes tRNA- transfers amino acids to ribosomes to make protein

1.Transcription-occurs in nucleus mRNA copies DNA nucleotide sequence 2. Translation nucleotide sequence in mRNA is uncoded mRNA binds to rRNA tRNA brings appropriate amino acid to mRNA Polypeptide is manufactured

DNA Sense Strand mRNA Transcript

enzyme mRNA Transcription begins here

mRNA

anticodon codon tRNA

Ribosome Amino Acid tRNA mRNA Codon Anticodon

Initiator codon Anticodon AA Binding sites Ribosome mRNA

Stop codon AA 1 T A G A U C 2 AA Complete protein

Rapid and uncontrollable development and production of cells.

1.Inheritance may increase risk 2.Proto-oncogenes and tumor suppressor genes mutate or become damaged by carcinogens 3.Known carcinogens: Viruses and bacteria Environmental chemicals Tobacco Radiation Dietary factors

Conversion begins with a mutation (a change in DNA) by: 1.Chemical 2.Physical 3.Biological Conversion

Development and Progression

Begins when a chemical substance stimulates growth of a mutated cell Those chemical substances influence a 2 nd stage of carcinogens called promoters. Promoters stimulate cell to divide uncontrollably Metastasis- cancer traveling to other sites; like a forest fire

ozone

Screens out 99% of harmful UV light Ozone produced by lightening 1% in ozone will result in a 2% in skin cancer Holes in ozone: Dupont- CFCs: hairspray, refrigerators, air conditioning Which country has the highest rate of skin cancer?

1.Avoid sun between 10am to 4pm. 2.Wear sunscreen w/ SPF Wear appropriate clothing.

Genetic testing Biopsy Blood test X-rays, PET, MRI Visual & tactile observation

Surgery Radiation Chemotherapy Homeopathy

Know family history Get regular medical screenings Learn self-exam techniques Avoid direct sunlight Watch your diet and weight Don’t smoke Drink alcohol in moderation (alcohol decrease heart disease, but increases risk of certain cancers) Become educated

INQUIRY 1.What do CFC’s do? 2.What is a proto-oncogene? 3.Name 3 carcinogens. 4.What are the ABCD’s of skin cancer? 5.What is the function of ozone? 6.Who is Henrietta Lacks?

INQUIRY 1.Which cells in the body are diploid and which are haploid? 2.During which stage does DNA replication occur? 3.Which stage of mitosis is seen in this picture? 4.At which stage is the cell binuclear? 5.In which phase do chromosomes line up in the center of the cell? 6.Where does the kinetochore attach?