Ch. 5: The Cell Cycle OBJECTIVE: 5A DESCRIBE THE STAGES OF THE CELL CYCLE, INCLUDING DEOXYRIBONUCLEIC ACID (DNA) REPLICATION AND MITOSIS, AND THE IMPORTANCE OF THE CELL CYCLE TO THE GROWTH OF ORGANISMS

OBJECTIVE: 5A DESCRIBE THE STAGES OF THE CELL CYCLE, INCLUDING DEOXYRIBONUCLEIC ACID (DNA) REPLICATION AND MITOSIS, AND THE IMPORTANCE OF THE CELL CYCLE TO THE GROWTH OF ORGANISMS 5C DESCRIBE THE ROLES OF DNA, RIBONUCLEIC ACID (RNA), AND ENVIRONMENTAL FACTORS IN CELL DIFFERENTIATION 5D RECOGNIZE THAT DISRUPTIONS OF THE CELL CYCLE LEAD TO DISEASES SUCH AS CANCER 9C IDENTIFY AND INVESTIGATE THE ROLE OF ENZYMES 10C ANALYZE THE LEVELS OF ORGANIZATION IN BIOLOGICAL SYSTEMS AND RELATE THE LEVELS TO EACH OTHER AND TO THE WHOLE SYSTEM

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions  I. The Cell Cycle in Eukaryotes  A. a regular pattern of growth, DNA replication, and cell division

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions  B. there are 4 main stages of the cell cycle  1. G1 (gap 1)- cell growth and normal functions  2. S (DNA S ynthesis)- dna is copied  3. G2 (gap 2)- additional growth of cell, organelles are copied, and cell prepares to divide  4. M (mitosis)- includes division of cell nucleus (mitosis) and division of the cytoplasm (cytokinesis)  a. mitosis occurs only if the cell is large enough and the DNA is undamaged

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions

 II. Cell Growth and division  A. Cells are small because:  1. The larger the cell, the more demands on the DNA  2. The larger the cell, the more trouble it has getting substances across the membrane

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions  B. Small cells allow for a greater surface area to volume ratio, which makes it more efficient for a cell to exchange oxygen nutrients, wastes, etc (more surface area than volume is better)  1. Cells that must be large (like some nerve cells) have shapes that help maximize surface area

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions

What surface area (SA) to volume ratio does a cell want?  1:5 or 5:1?

What surface area (SA) to volume ratio does a cell want?  5:1  You want MORE surface area- you can move things quicker!

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions  C. Cells divide at different rates  1. rate of cell division depends on the need for that type of cell  a. Skin cells have a 2 week life span, muscle cells in your intestines live for ~16 years.  b. some cells, like nerve cells and some white blood cells, are unlikely to divide (G 0 )  c. prokaryotic cells divide much faster than eukaryotic cells

5.1 The Cell Cycle Key Concept: cells have distinct phases of growth, reproduction, and normal functions

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  I. Chromosomes condense at the start of mitosis  A. Chromosome- a long continuous thread of DNA  B. DNA (deoxyribonucleic acid) wraps around proteins called histones, forming chromatin.  1. DNA + proteins (histones) = chromatin DNA double helix DNA and histones Chromatin Supercoiled DNA

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  C. Chromatin condenses and coils even more and forms a chromosome  D. Chromosomes are X shaped and contain several parts  1. (sister) chromatid - one half of a chromosome  2. these two sister chromatids are held together at the centromere  3. telomeres - “caps” on the end of the DNA that help protect it

Condensed, duplicated chromosome 5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis Sketch chromatid telomere centromere telomere

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  2. Mitosis and cytokinesis produce two identical daughter cells  A. Interphase prepares the cell to divide  1. interphase includes G1, S, and G2  2. DNA is replicated during the S phase

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  B. Mitosis- division of the nucleus - is divided into four phases (PMAT)  1. Prophase- chromosomes condense and become visible. Spindle fibers form  2. Metaphase- chromosome line up in the middle of the cell  3. Anaphase- sister chromatids separate (becoming chromosomes) to opposite ends of the cell  4. Telophase- new nuclei start to form and chromosomes uncoil

Interphase- NOT A PART OF MITOSIS!!!

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  Prophase

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  Metaphase

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  Anaphase

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  Telophase

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  C. Cytokinesis- division of the cytoplasm  1. Different in animal and plant cells  a. Animal cells - membrane pinches off, forming a cleavage furrow  b. Plant cells - have a cell wall, so a cell plate is formed

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis  Cytokinesis

5.2 Mitosis and Cytokinesis Key Concept: cells divide during mitosis and cytokinesis

 III. Why do cells divide?  A. Multicellular organisms use cell division for growth, development, and repair  B. Unicellular organisms use cell division for reproduction (some multicellular do too)

 III. Why do cells divide?  Multicellular organisms use cell division for growth, development, and repair  Unicellular organisms use cell division for reproduction (some multicellular do too)

What are these?

What phase is this? What part of the cell cycle is this in? How many chromosome are there?

Think!  When a cell with 24 chromosomes divides by mitotic cell division (mitosis), how many chromosomes will each daughter cell have?

Think!  24!  Chromosome will duplicate during the S phase (24  48)  So cell division gives 24 in EACH new daughter cell  That’s why they look like X’s, they’re doubles!

Mitosis in action

5.3 Regulation of the Cell Cycle Key Concept: cell cycle regulation is necessary for healthy growth  I. Internal and external factors regulate cell division  A. External factors - come from outside the cell: physical and chemical signals  1. Growth factors- proteins the stimulate cell division  B. Internal factors - come from inside the cell  1. Cyclins are proteins that control the cell cycle  C. Apoptosis- programmed cell death webbed fingers Webbing and sunburns!!!

5.3 Regulation of the Cell Cycle Key Concept: cell cycle regulation is necessary for healthy growth  II. Cancer is uncontrolled cell division  A. Cancer is a disorder in which some of the body’s own cells lose the ability to control growth, forming tumors, or masses of cells

Its not a tumor

5.3 Regulation of the Cell Cycle TEKS 5A, 5B, 5C, 5D, 9C Cell division is uncontrolled in cancer. Cancer cells form disorganized clumps called tumors. cancer cell bloodstream normal cell –Benign tumors remain clustered and can be removed. –Malignant tumors metastasize, or break away, and can form more tumors.

5.3 Regulation of the Cell Cycle Key Concept: cell cycle regulation is necessary for healthy growth  1. Cancer cells do not respond to the signals that control the growth of most cells  2. Cancer cells do not carry out necessary functions  3. Come from normal cells with damaged DNA  a. carcinogens- substances known to promote the development of cancer.

5.4 Asexual reproduction Key Concept: many organisms reproduce by cell division  I. Asexual reproduction - the production of offspring from a single parent. Most unicellular organisms and some multicellular organisms use mitosis for reproduction  A. Binary Fission - method most prokaryotic organisms use to reproduce  1. Produces two genetically identical daughter cells  2. similar results as mitosis, but prokaryotes lack a nucleus

5.4 Asexual reproduction Key Concept: many organisms reproduce by cell division  3. Advantageous in consistently favorable conditions. Can produce many offspring very quickly  Takes less time to find a mate, and each “adult” individual can make a new organism- sexual repro requires 2 “adults” to make one offspring  4. Sexual reproduction is advantageous in changing conditions

5.4 Asexual reproduction Key Concept: many organisms reproduce by cell division  B. Budding- asexual reproduction in eukaryotes  1. forms a new organism from a small projection growing on the surface of the parent. Ex: Hydra bud Hydra Yeast

5.4 Asexual reproduction Key Concept: many organisms reproduce by cell division  C. Fragmentation- asexual reproduction in eukaryotes  1. splitting of the parent into pieces the each grow into a new organism

5.5 Multicellular Life Key Concept: cells work together to carry out complex functions  I. Multicellular organisms depend on interactions among different cell types  A. Tissues : groups of cells that preform a similar function  B. Organs : groups of tissues that preform a specific function  Ex: Leafs- the food producing organs of plants (cells to do photosynthesis, carry water, protect cell, etc)  C. Organ Systems : groups of organs that carry out similar functions

5.5 Multicellular Life TEKS 5B, 5C, 10C CELLTISSUEORGAN vascular tissue leaf stem lateral roots primary root SYSTEMS root system shoot system

5.5 Multicellular Life Key Concept: cells work together to carry out complex functions  II. Specialized cells perform specific functions  A. Cell differentiation - process by which a cell becomes specialized for a specific structure or function  1. Cell differ because different genes are expressed in different cells Outer: skin cells Middle: bone cells Inner: intestines

5.5 Multicellular Life Key Concept: cells work together to carry out complex functions  B. Stem Cells - unique type of cell that can differentiate into a variety of cell types  1. Totipotent- grow into any cell type  2. Pluripotent- any cell type except totipotent  3. Multipotent- cells of a closely related cell family (ex: blood cells) 

5.5 Multicellular Life Key Concept: cells work together to carry out complex functions