The Cell T H E C E L L C Y C L E C A N C E R

The Cell T H E C E L L C Y C L E C A N C E R

Nuclear envelope Transcription DNA RNA Processing Pre-mRNA Translation mrna Nuclear pores Ribosome Polypeptide

Transcription RNA is synthesized from DNA in the nucleus mrna (messenger) trna (transfer) rrna (ribosomal)

Translation Converts base sequence of nucleic acids into the amino acid sequence of proteins Involves mrna, trna, and rrna Occurs in the cytoplasm

Genetic Code Each three-base sequence on DNA is represented by a codon Codon complementary three-base sequence on mrna

Figure 3.36 SECOND BASE UUG UUA UUC UUU Phe Leu CUG CUA CUC CUU Leu AUA AUC AUU Ile GUG GUA GUC GUU Val UCG UCA UCC UCU Ser CCG CCA CCC CCU Pro ACG ACA ACC ACU Thr GCG GCA GCC GCU Ala UAC UAU Tyr CAG CAA CAC CAU His Gln AAG AAA AAC AAU Asn Lys GAG GAA GAC GAU Asp Glu UGC UGU Cys Trp CGG CGA CGC CGU Arg AGG AGA AGC AGU Ser Arg GGG GGA GGC GGU Gly UAA Stop UGA Stop AUG Met or Start UAG Stop UGG U C A G G A C U G A C U G A C U G A C U U C A G

TRANSCRIPTION DNA 3 5 RNA transcript RNA polymerase RNA PROCESSING Exon RNA transcript (pre-mrna) Intron Aminoacyl-tRNA synthetase NUCLEUS CYTOPLASM FORMATION OF INITIATION COMPLEX Amino acid trna AMINO ACID ACTIVATION A mrna Growing polypeptide Activated amino acid 3 E P Ribosomal subunits 5 TRANSLATION E A Anticodon Codon Ribosome

The Cell Cycle An illustration of the life cycle of a cell Consists of four major phases G1 phase S phase G2 phase M phase

G 1 checkpoint (restriction point) G 1 Growth S Growth and DNA synthesis G 2 Growth and final preparations for division M G 2 checkpoint Copyright 2010 Pearson Education, Inc. Figure 3.31

The Cell Cycle Interphase G1 S G2 M phase Mitosis Cytokinesis

Cell Division Mitotic (M) phase of the cell cycle Essential for body growth and tissue repair Does not occur in most mature cells of nervous tissue, skeletal muscle, and cardiac muscle We will come back to cancer

Functions of Cell Division Growth Replacement Repair Reproduction

The Process of Cell Division Includes two distinct events 1. Mitosis division of chromatin Prophase Metaphase Anaphase Telophase 2. Cytokinesis division of cytoplasm by cleavage furrow

G 1 checkpoint (restriction point) G 1 Growth S Growth and DNA synthesis G 2 Growth and final preparations for division M G 2 checkpoint Figure 3.31

The Process of Cell Division DNA replication Takes place during S (synthesis) phase of cell cycle Occurs in the nucleus

Chromosome Free nucleotides DNA polymerase Old strand acts as a template for synthesis of new strand Leading strand Old DNA Helicase unwinds the double helix and exposes the bases Adenine Thymine Cytosine Guanine Replication fork Two new strands (leading and lagging) synthesized in opposite directions Lagging strand DNA polymerase Old (template) strand Copyright 2010 Pearson Education, Inc. Figure 3.32

DNA Replication End result is two complete sets of DNA Assures appropriate chromosome number in daughter cells 46 46 46

Early Prophase Early mitotic spindle Aster Early Prophase Chromosome consisting of two sister chromatids Centromere Copyright 2010 Pearson Education, Inc. Figure 3.33

Late Prophase Polar microtubule Spindle pole Fragments of nuclear envelope Late Prophase Kinetochore Kinetochore microtubule Copyright 2010 Pearson Education, Inc. Figure 3.33

Prophase DNA is condensed centromere Sister chromatids

LE 12-4 0.5 µm Chromosome duplication (including DNA synthesis) Centromere Sister chromatids Separation of sister chromatids Centromeres Sister chromatids

Metaphase Spindle Metaphase Metaphase plate Copyright 2010 Pearson Education, Inc. Figure 3.33

Anaphase Anaphase Daughter chromosomes Copyright 2010 Pearson Education, Inc. Figure 3.33

Telophase and Cytokinesis Nuclear envelope forming Nucleolus forming Contractile ring at cleavage furrow Telophase Copyright 2010 Pearson Education, Inc. Figure 3.33

The Process of Cell Division Problems during mitosis May or may not be fatal Examples Non-disjunction Down syndrome X and Y chromosomes

Cytokinesis cell movement Cells actually divide Follows nuclear division

Cytokinesis Begins during late anaphase Ring of actin microfilaments contract to form a cleavage furrow Two daughter cells are pinched apart Each contains a nucleus identical to the original

LE 12-9a Cleavage furrow 100 µm Contractile ring of microfilaments Daughter cells Cleavage of an animal cell (SEM)

Cancer Second most common cause of death in U.S. Prostate cancer Estimated 217,730 men will be diagnosed Breast cancer 12.2% women will be diagnosed

Cancer Most common types Prostate (men) Breast (women) Lung Colorectal

Cancer Normal damage control exists in the cell cycle Control(s) are abnormal in cancer Example: proto-oncogenes, tumor suppressor genes (P53) Uncontrolled cell division Absence of or defective regulatory proteins Cancer cells compete with and crowd out normal cells

LE 12-14 G 1 checkpoint G 1 Control system S M G 2 M checkpoint G 2 checkpoint

Cancer Genes coding for checkpoint proteins Mutation of genes results in uncontrolled cell division Anything that can alter these genes can trigger cancer

Cancer Cancer cells form tumors Masses of abnormal cells within otherwise normal tissue Benign tumor Cells are encapsulated and remain at original site Malignant tumor Invades surrounding tissue and may metastasize

LE 12-19 Tumor Lymph vessel Glandular tissue A tumor grows from a single cancer cell. Cancer cells invade neighboring tissue. Cancer cell Cancer cells spread through lymph and blood vessels to other parts of the body. Blood vessel Metastatic tumor A small percentage of cancer cells may survive and establish a new tumor in another part of the body.

LE 19-13 Colon Colon wall Loss of tumorsuppressor gene APC (or other) Activation of ras oncogene Loss of tumorsuppressor gene p53 Normal colon epithelial cells Small benign growth (polyp) Loss of tumorsuppressor gene DCC Larger benign growth (adenoma) Additional mutations Malignant tumor (carcinoma)

Cancer Classification 1. Carcinoma Epithelium 2. Sarcoma Connective tissue, bone or muscle 3. Myeloma Plasma cells in bone marrow 4. Lymphoma Lymph tissue 5. Leukemia Abnormal white blood cells

Cancer Symptoms vary with type Unusual bleeding or discharge A lump that does not go away A sore that does not heal within two weeks A change in bowel or bladder habits Persistent hoarseness or cough Indigestion or difficulty swallowing Change in a wart or mole

Cancer Causes Carcinogens Oncogenic viruses Hereditary factors Early detection is important!

Homework Due in Lab HW #5 Page 13 and 14 in the HW section of the Study Guide Pre-Lab 3 Handout