10-1 cell growth growth and development!! definitions histones telomeres somatic cells chromatin...
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10-1 Cell GrowthGrowth and Development!!
Definitions
Histones Telomeres Somatic cells Chromatin Chromosomes Centromeres Spindle fibers
Parts of a Chromosome Chromosome: Long threads of DNA that
consist of genes. Humans have 46 chromosomes Histones: proteins DNA wraps around.
Makes it condensed!!! Chromatin: Loose DNA when it is not
condensed. DNA only condenses during mitosis and meiosis.
Chromatin - A complex of DNA and proteins in the cell nucleus that condenses to form chromosomes during cell division(loose DNA).
Chromosomes – Condensed Chromatin(X) They are the same stuff, just in different
forms Centromeres: Center point where
chromatids are attached. Spindle Fibers - Fibers that pull part the
chromosomes during mitosis.
Parts of the Chromosomes
Telomere: DNA molecules at the end of the chromosomes that do not code for genes. They keep the DNA from unraveling.
Chromatid:One half og the duplicated chromosome.
Centromere: Each sister chromatid is held together at the centromere.
ALL OF THIS IS FORMED AFTER REPLICATION!!!
Some Definitions
Histones: proteins that DNA will wrap around. This helps the DNA to fit.
Telomeres: End of DNA molecules to prevent them from attaching to each other. They do not contain genes.
Somatic Cells – body cells Produced through mitosis Has 46 chromosomes (23 pairs)
Parts of the Chromosomes
Chromatin condenses in chomosomes before mitosis begins
Chromatin Chromosomes
Histone
Parts of a Chromosome
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)
Problem with Being Too Big!!
The volume gets too big for the surface area. The cell membrane cannot control all the
movement in and out when the volume is too large.
Your cells cannot too large either. The surface area must be in the correct ratio of the volume.
Neurons are very long and skinny so that ration is correct.
2. 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
3rd Problem - Too Big
3. DNA overloadYour DNA controls all activities in
the cell. When the cell gets too big then the DNA cannot control all activites.
3rd problem: DNA overload
Radius 2cm
S.A. = ___50cm2__
V = __33cm3____
Ratio SA:V = 50:33_or 1.51:1
Radius 1cm
S.A. = _____
V = ______
Ratio SA:V = ___
S.A. = 4 (pi) r 2
Radius 1cm
S.A. = __13cm2___
V = __4cm3____
Ratio SA:V = _13:4 or 3.25:1__
Radius 3cm
S.A. = _____
V = ______
Ratio SA:V = ___
Radius 3cm
S.A. = __113cm2_
V = ___113cm3___
Ratio SA:V = _113:113 or 1:1__
1. As the spheres get larger what happens to the SA:V ratio?
Cell Cycle
Life Cycle of the cell! Most of the time your cells are growing. Divide after the cell has gotten too big!
The Cell Cycle and Mitosis
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.
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)
M Phase, Cell Division and Mitosis
3 Main Events of a Cell Cycle1. Interphase
G1 - growth S – DNA
replication G2 – growth
and prepare for division
2. Mitosis Phase – nucleus dividingProphaseMetaphase AnaphaseTelophase
3. Cytokinesis – cell division
The Cell Cycle - series of events that cells go through as they grow and divide
The cell cycle is divided into two halfs Interphase -
period of the cell cycle between cell divisions
Mitosis phase and cytokinesis – period of time when mitosis and cell division occurs
Parts of InterphaseG1
Phase(growth)Cell growsSynthesize new
proteins and organelles
Doing their jobsLongest phase
of cell cycle
S Phase
S Phase(synthesis)Chromosomes(DNA) are replicatedKey proteins associated with
replication are made (centromeres
Gap 2 Phase
G2 Phase(growth)Shortest of the 3 phases of
interphaseOrganelles and molecules for cell
division are produced (centrioles)Check-up phase before mitosis
What’s
Missing?
Cell Cycle
http://www.cellsalive.com/mitosis.htm
http://www.johnkyrk.com/mitosis.html
Parts of InterphaseG1
Phase(growth)Cell growsSynthesize new
proteins and organelles
Doing their jobsLongest phase
of cell cycle
S Phase
S Phase(synthesis)Chromosomes(DNA) are replicatedKey proteins associated with
replication are made (centromeres
Gap 2 Phase
G2 Phase(growth)Shortest of the 3 phases of
interphaseOrganelles and molecules for cell
division are produced (centrioles)Check-up phase before mitosis
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.
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!!!
Mitosis
MITOSIS
Mitosis
Division of the nucleus.
Followed by cytokinesis!!!
The daughter cells are identical to one another and to the original
parent cell.
Mitosis
ProphaseMetaphaseAnaphaseTelophase
Prophase
Longest phase of mitosis Chromatin condenses into
chromosomes Spindle fibers form and
attach to centrioles Nuclear membrane
dissappears Nucleolus breaks down
Prophase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
ProphaseThe cell prepares for nuclear division
Animal Cell Packages DNA into
chromosomes
Plant cell Packages DNA into
chromosomes
Metaphase
Centromeres line up across the center of the cell
Spindle fibers connect to centromeres
AnaphaseChromosomes are pulled apart by
spindle into individual chromatids.
The chromatids are now consideredChromosomes!!
Anaphase
Centromeres splitSister chromatids are pulled
apart to opposite poles of the cell
Each chromatid is now a separate chromosome
Telophase
Nuclear envelopes (2) and nucleolus reform
Chromosomes begin to uncoilSpindle fibers disappear.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- ReviewInterphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Cytokinesis
Cytoplasm dividesTwo new daughter cells are
now separate
Cytokinesis The cytoplasm pinches
in half Animal - cleavage furrow Plants - cell plate
http://www.johnkyrk.com/mitosis.html
In plant cells, a cell plate forms. The cell plate is synthesized by the fusion of multiple membrane-
bounded vesicles. Their fusion supplies new plasma membrane for each of the two daughter cells. Synthesis
of a new cell wall between the daughter cells then occurs at the cell plate.
Apoptosis
Cell death. Factors that signal genes to produce self destructive enzymes. Not sure why.
EX: webbing of toes on an embryo.
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
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.
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.
OncogenesSRC, proto-oncogene tyrosine-protein kinase
Treatments for Cancer
Radiation and chemotherapy – used to kill the cancer cells and stop division. They kill good and bad cells.
Stem Cells
Stem cells are a type of body cell that have the ability to
1. Divide and renew themselves
2. Remain undifferentiated3. Develop into a variety of
specialized cells.
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
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
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 = 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
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 = 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
What is the diploid chromosome number?
42
What is the haploid chromosome number?
21
How many chromosomes would be in somatic cells?
42
How many chromosomes would be in brain cells?
42
How many chromosomes would be in gamete cells?
21
How many chromosomes would be in egg cells?
21
How many chromosomes would be in muscle cells?
42
How many chromosomes would be in sperm cells?
21
Is this a male or female rat?
male
Quick ReviewChromsomes are tightly coiled
strands of DNADiploid (somatic) cells contain the
entire set of chromosomesHaploid (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.