Growth and Development!! Cell Growth and Repair Growth and Development!!

Answer the following questions in your group: How many chromosomes are in a human body cell? Name the 2 types of cells in your body. Why do organisms need new cells? Name the two main phases of the cell cycle. What do cell do in G0? Describe the phases of interphase and how many chromosomes do they have in each. Name the 4 stages of mitosis. Why can’ cells grow forever?

Claim – Why is all hemoglobin different

Evidence – What evidence did I teach you?

Reasoning – How did this happen?

Bellringers 2/22 – Explain how you grow and repair your body. 2/23 – Explain why your DNA must replicate before your cells divide. Name when you may need new cells. 2/26 – Explain how a lizard would re-grow its tail. What is that called? Explain why the DNA must replicate. 2/27 – Explain why organisms cells must divide. Provide 2 examples. Name the 3 stages of the cell cycle.

NGSS Standards HS-LS1-4. Use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms. [Assessment Boundary: Assessment does not include specific gene control mechanisms or rote memorization of the steps of mitosis.]

Collect evidence on when and how organisms get new cells. Today’s Task Collect evidence on when and how organisms get new cells.

When Do New Cells Need to Form? A. Growth - More cells B. Maintenance (repair and replacement)--> intestinal lining/RBC’s) C. Asexual reproduction D. Formation of sex cells (Meiosis)

Why Can’t Your Cells Grow Forever? Cell membrane cannot control material DNA overload

TOO BIG!: Cell membrane cannot control all movements of materials The larger a cell grows the more trouble it has… moving enough nutrients in Moving all the waste materials out

DNA overload!!! DNA overload Your DNA controls all activities in the cell. When the cell gets too big then the DNA cannot control all activites.

What stops cell from growing? Proximity to neighbor cells. Cells in a petri dish will continue to grow until they come into contact with other cells. Similarily, skin around a wound After a cell has quit growing, it is time to divide!!!

Cell Cycle – life of a cell The life of a cell. It has a pattern of cell growth, DNA replication, and cell division. Results in two new daughter cells.

Definitions Histones Telomeres Somatic cells Gametes Chromatin Chromosomes Centromeres Spindle fibers

Parts of the Chromosomes

Parts of a Chromosome Chromosome: X’s during mitosis. Humans have 46 chromosomes Histones: proteins DNA wraps around. Makes it condensed!!! Chromatin: Loose DNA when it is not condensed during interphase. DNA only condenses during mitosis and meiosis.

Histone

Chromatin condenses in chomosomes before mitosis begins Chromosomes - mitosis Chromatin - interphase

Parts of a Chromosome

Interphase

This cycle consists of three phases: G1, S, G2 . The cell cycle is a repeated pattern of growth and division that occurs in eukaryotic cells. This cycle consists of three phases: G1, S, G2 The first phase represents cell growth while the last two phases represent cell division.

The cell cycle has THREE main stages. Interphase, mitosis, and cytokinesis

3 Main Events of a Cell Cycle 1. Interphase G1 - growth S – DNA replication G2 – growth and prepare for division 2. Mitosis Phase – nucleus dividing Prophase Metaphase Anaphase Telophase 3. Cytokinesis – cell division

M Phase, Cell Division and Mitosis

The purpose of interphase is for cell growth. Cells spend the majority of their cell cycle in interphase. NORMAL ACTIVITY AND GROWTH The purpose of interphase is for cell growth. By the end of interphase a cell has two full sets of DNA (chromosomes) and is large enough to begin the division process.

Parts of Interphase G1 Phase(growth) Cell grows Synthesize new proteins and organelles Doing their jobs Longest phase of cell cycle

S Phase S Phase(synthesis) Chromosomes(DNA) are replicated Key proteins associated with replication are made (centromeres) 46 CHROMOSOMES TO 92!!

Gap 2 Phase G2 Phase(growth) Shortest of the 3 phases of interphase Organelles and molecules for cell division are produced (centrioles) Check-up phase before mitosis

The Cell Cycle The sequence of growth and division of a cell. 95% of cell cycle in interphase(growth) 5% of cell cycle in mitosis(division)

G - 0 Stage This is a stage of interphase that SOME cells enter. Cells such as nerve and white blood do not divide often so they enter this stage of rest.

MITOSIS

Mitosis Division of the nucleus. Followed by cytokinesis!!! The daughter cells are identical to one another and to the original parent cell.

Mitosis & Cytokinesis Mitosis is nuclear division!!!! Cytokinesis – Cell division In mitosis the four strands (two sister chromatids) have to break apart so that each new cell only has one double-stranded chromosome.

Mitosis Prophase Metaphase Anaphase Telophase

Prophase is characterized by four events: Chromosomes condense and are more visible. The nuclear membrane (envelope) disappears. Centrioles have separated and taken positions on the opposite poles of the cell. Spindle fibers form and radiate toward the center of the cell.

Prophase Longest phase of mitosis Chromatin condenses into chromosomes Spindle fibers form and attach to centrioles Nuclear membrane dissappears Nucleolus breaks down

Longest phase of mitosis

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Prophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

During prophase, chromosomes condense and spindle fibers form. Mitosis divides the cell’s nucleus in four phases. During prophase, chromosomes condense and spindle fibers form.

Chromosomes line up across the middle of the cell. Metaphase (the shortest phase of mitosis) is characterized by two events: Chromosomes line up across the middle of the cell. Spindle fibers connect the centromere of each sister chromatid to the poles of the cell.

Metaphase Centromeres line up across the center of the cell Spindle fibers connect to centromeres

During metaphase, chromosomes line up in the middle of the cell. Mitosis divides the cell’s nucleus in four phases. During metaphase, chromosomes line up in the middle of the cell.

Anaphase Centromeres split Sister chromatids are pulled apart to opposite poles of the cell Each chromatid is now a separate chromosome

Anaphase is characterized by three events: Centromeres that join the sister chromatids split. Sister chromatids separate becoming individual chromosomes. Separated chromatids move to opposite poles of the cell.

Anaphase Chromosomes are pulled apart by spindle into individual chromatids. The chromatids are now considered Chromosomes!!

Mitosis divides the cell’s nucleus in four phases. During anaphase, sister chromatids separate to opposite sides of the cell.

Telophase Nuclear envelopes (2) and nucleolus reform Chromosomes begin to uncoil Spindle fibers and centriole disappear.

Telophase (the last phase of mitosis) consists of four events: Chromosomes (each consisting of a single chromatid) uncoil. A nuclear envelope forms around the chromosomes at each pole of the cell. Spindle fibers break down and dissolve. Cytokinesis begins.

Mitosis divides the cell’s nucleus in four phases. During telophase, the new nuclei form and chromosomes begin to uncoil.

The process of cytokinesis differs somewhat in plant and animal cells. Cytokinesis is the division of the cytoplasm into two individual cells. The process of cytokinesis differs somewhat in plant and animal cells. In animal cells the cell membrane forms a cleavage furrow that eventually pinches the cell into two nearly equal parts, each part containing its own nucleus and cytoplasmic organelles.

Animal Cell Telophase/Cytokinesis

In animal cells, the membrane pinches closed. Cytokinesis differs in animal and plant cells. In animal cells, the membrane pinches closed. In plant cells, a cell plate forms.

The cell wall forms in the cell plate. In plant cells a structure known as a cell plate forms midway between the divided nuclei, which gradually develops into a separating membrane. The cell wall forms in the cell plate.

Plant Cell Telophase/Cytokinesis

Cells divide at different rates. The rate of cell division varies with the need for those types of cells. Some cells are unlikely to divide (G0).

Cell size is limited. Volume increases faster than surface area.

Surface area must allow for adequate exchange of materials. Cell growth is coordinated with division. Cells that must be large have unique shapes.

Cytokinesis Cytoplasm divides Two new IDENTICAL daughter cells are now separate

Cytokinesis The cytoplasm pinches in half Animal - cleavage furrow http://www.johnkyrk.com/mitosis.html Cytokinesis The cytoplasm pinches in half Animal - cleavage furrow Plants - cell plate

Stem Cells Stem cells are a type of body cell that have the ability to Divide and renew themselves Remain undifferentiated Develop into a variety of specialized cells.

CELL DIFFERENTIATION In fetus, remember the location of the cell in development turn genes on and off. This leads to different proteins to be made – therefore different cells.

Cyclins Protein that controls cell division.. They can make cells grow in a petri dish. Doesn’t work on all cells.

Controls on Cell Division

Apoptosis Cell death. Some factor signals genes to produce self destructive enzymes. Not sure why. EX: webbing of toes on an embryo, tad pole tail, mutated DNA in a cell

Cancer Class of disease caused by uncontrolled cell division. Arises when the regulation of the cell cycle breaks down. The cells continue to divide with the absence of internal and external growth factors. Benign tumor: cancer cells remain in one mass and usually can be removed. Malignant: cancer cells break away from the cancer cells to other parts of the body.

Why are cancer cells so dangerous? Cancer cells cannot perform the duties needed by the body. Too many cancer cells and the body cannot perform the processes needed to live. A large tumor can apply pressure to other organs and affect the processes of organ.

What causes cells to form cancer? Cancer cells comes from regular cells that have damage in one of the two genes that makes the proteins for cell cycle regulation. Oncogene: gene that accelerates the cell cycle. Gene 2 : breaks cell cycle. A mutation in these 2 genes can be inherited or a carcinogen can cause a mutation in these genes.

Cancer cells are YOUR OWN CELLS that have cyclins messed up so they continue to divide and do not GROW enough!

Causes of Cancer Carcinogen: Substances known to cause the cell cycle genes to mutate and cell divide uncontollably. Various forms of cancer have many causes Smoking Radiation Viral infections The common thread in all cancers is that control over the cell cycle has broken down. Over 50% of cancer cells have a defect in the p53 gene.

p53 antioncogene p53 is a tumor suppressor gene found mutated in about half of human cancers. It encodes a gene regulatory protein that is activated by damaged DNA and is involved in blocking further progression of the cell cycle.

Treatments for Cancer Radiation and chemotherapy – used to kill the cancer cells and stop division. They kill good and bad cells.

Chromosomes

Reflection 3/14 – Describe the chromosome disorder you have in your study.

Chromosomes Defined: Tightly coiled DNA Forms during cell division New chromosomes created for new cells 2 Parts: 1) Chromatids: two identical parts of a chromosome 2) Centromere: Joins chromatids together Chromosomes

KAROTYPE Map of chromosome used to study disorders. You had a normal and abnormal set. How many chromosomes are normal?

Down Syndrome: What’s Wrong? Writing notation: 1st: total chromosome # 2nd: Sex chromosomes 3rd: extra or missing Down Syndrome: 47, XY, +21

Turner’s Syndrome: What’s Wrong? Write the notation for Turner’s Syndrome. 45, X, -23 or 45, XO, -23

Patau’s Syndrome: What’s Wrong? Write the notation for Patau’s Syndrome. 47, XY, +13

Klinefelter’s Syndrome: What’s Wrong? Write the notation for Klinefelter’s Syndrome. 47, XXY, +23

Diploid Cells Diploid Cells = Cells with the full set of chromosomes Paired chromosomes Half of our chromosomes come from each parent (23 from each parent) Somatic (non-sex) cells are diploid Created by mitosis Ex: Skin, Muscle, Nerve, Blood Cells

What is the human diploid chromosome number? Remember…Diploid = total number of chromosomes Answer = 46

Karyotype Female Male Defined: Picture of an individuals chromosomes Identify sex & chromosome defects Size of final pair identifies sex Same size: XX = female Different size: XY = male Normal human will have 46 chromosomes Female Male

What is the human somatic chromosome number? Remember…Somatic cells are non-sex cells… …Somatic cells are diploid… …Diploid cells have the full set of chromosomes Answer = 46

How many chromosomes are in brain cells? Remember…Brain cells are non-sex cells… …Somatic cells are non-sex cells… …Somatic cells are diploid… …Diploid cells have the full set of chromosomes Answer = 46

Haploid Cells Haploid Cells = Cells with ½ the total number of chromosomes Gametes (sex cells) are the only haploid cells Ex: Sperm, Egg, Pollen Chromosome number is reduced by meiosis How do humans get 46 chromosomes? Haploid sperm cell (23) + Haploid egg cell (23) = Diploid zygote (46)

What is the human haploid chromosome number? Remember…Haploid = half number of chromosomes Answer = 23 chromosomes

What is the human gamete chromosome number? Remember…Gamete cells are sex cells… …Sex cells are haploid… …Haploid cells have ½ the set of chromosomes Answer = 23

How many chromosomes are in female egg cells? Remember…Egg cells are sex cells… …Sex cells are gametes… …Gamete cells are haploid… …Haploid cells have ½ the set of chromosomes Answer = 23

Rat Karyotype What is the diploid chromosome number? 42

Rat Karyotype What is the haploid chromosome number? 21

Rat Karyotype How many chromosomes would be in somatic cells? 42

Rat Karyotype How many chromosomes would be in brain cells? 42

Rat Karyotype How many chromosomes would be in gamete cells? 21

Rat Karyotype How many chromosomes would be in egg cells? 21

Rat Karyotype How many chromosomes would be in muscle cells? 42

Rat Karyotype How many chromosomes would be in sperm cells? 21

Rat Karyotype Is this a male or female rat? male

Quick Review Chromsomes are tightly coiled strands of DNA Diploid (somatic) cells contain the entire set of chromosomes Haploid (gametes) cells contain only ½ the total number of chromosomes

Limit of cell size? 1. TOO SMALL - There will not be enough room for all the organelles to carry out the processes needed.

Cells Divide at Different Rates The rate of cell division is determined by the body’s need for that type of cell. Nerve cells do not divide because they do not die like our skin cells. A new layer of skin is replaced every 3 weeks. The lining of your intestines has to be replaced often because of the wear and tear. This is also skin cells.