Download Chromosomes - Fall River Public Schools

CELL CYCLE
INTERPHASE
CELL DIVISION
(cell is getting ready to
divide)
G1
Cell
begins
to grow
S
DNA is
copied
(cell is dividing)
G2
Cell
finishes
growing
M Phase
(MITOSIS)
Prophase,
Metaphase,
Anaphase,
Telophase
Cytokinesis
Cytoplasm
divides
CHROMOSOMES:
•
•
•
•
•
Usually, DNA is in a loose form called chromatin
When the cell is going to divide, it coils up nice & tight to form a chromosome
A piece of a chromosome is called a gene
A chromosome is made up of 2 sister chromatids, each containing many genes
These sister chromatids are joined together at the centromere
Label the diagram using the terms below:
Centromere
Chromatid
Chromosome
Gene
1.
2. ______________________
3. _______________
4. ______________
Chromosomes (continued)
• Humans have a total of 46 chromosomes in MOST of their cells. 46 is the
human diploid number- “2 sets of chromosomes”
• We get 23 chromosomes from mom (1 set) & 23 chromosomes from dad (1
set)
• The only cells that DO NOT have 46 chromosomes are our sex cells
(gametes), which are either sperm cells (in males) or egg cells (in females)
• These cells have ½ the amount of chromosomes; a total of 23 chromosomes.
23 is the human haploid number- “1 set of chromosomes”
• When the sperm (haploid) & egg (haploid) join during fertilization, the
resulting cell (called a zygote) contains a total # of 46 chromosomes
(diploid)
Nucleus of the egg cell
containing 23 chromosomes
Nucleus of the
sperm cell
containing 23
chromosomes
2 types of chromosomes:
1. Autosomes:
• chromosomes that determine EVERYTHING about you EXCEPT your gender (sex)
Q: What are some things that autosomes would determine about you?
A: height, hair color, eye color, freckles, skin color, hair texture, etc.
• Out of the 46 chromosomes humans have, 44 of them are autosomes (chromosome
pairs #1- #22)
2. Sex
chromosomes:
• chromosomes that ONLY determine your gender
• you have 2 sex chromosomes (pair #23)
Q: What are your sex chromosomes if you are a MALE?
A: XY
Q: What are your sex chromosomes if you are a FEMALE?
A: XX
KARYOTYPE: this is a picture of all of someone’s chromosomes
• it’s used to determine genetic disorders
• Pairs #1- #22 are called autosomes
• Pair #23 (last pair) are the sex chromosomes
• Each pair of chromosomes are called Homologous Chromosomes- they are ‘identical’ to
each other (1 is from mom; 1 is from dad)
Answer the following questions based on the
information in the Karyotype.
Q1: How many chromosomes are in the picture?
A1: 46
Q2: Why are the chromosomes in pairs?
A2: Because 1 chromosome came from mom and
the other came from dad
Q3: Is the person below a male or female?
A3: male
Cell division in Prokaryotes:
•Happens very quickly because
these cells are very simple
•Remember- prokaryotes are bacteria cells
•The process is called Binary Fission
• this creates clones
Cell division in Eukaryotes:
•Happens much slower because these cells are very complex
•The process is called Mitosis, which involves many detailed steps
CELL CYCLE:
• The cycle begins with Interphase
• The cell spends most of it’s time in Interphase
• Interphase is divided into 3 parts:
1. G1
2. S
• Cell division is divided into 2 parts:
1. Mitosis
2. Cytokinesis
3. G2
INTERPHASE:
•G1- stands for Gap 1
•in this phase the cell begins to grow
•S- stands for Synthesis
•in this phase DNA is copied
•G2- stands for Gap 2
•in this phase the cell finishes growing
-Remember: There is a total of 46 chromosomes in these cells (somatic cells- “body
cells”
- examples: muscle cell, bone cell, skin cell, kidney cell, liver cell)
-The centrioles (“scissors”) are also copied in interphase!
Q: Do you remember what the centriole looks like? Draw a picture:
Now the cell contains 2 sets of
centrioles!
CELL DIVISION:
• Cell division is divided into 2 parts
1. Mitosis
2. Cytokinesis
1. MITOSIS:
• Is made up of 4 phases:
1. Prophase 2. Metaphase
3. Anaphase
4. Telophase
http://player.discoveryeducation.com/index.cfm?guidAssetId=D80AF785-7629-4AEB-975D04B82CDBBC9C&blnFromSearch=1&productcode=US
•You will be required to know ALL stages of the cell cycle IN ORDER!!
**HINT: to help you learn this, take the 1st letter of each phase and write a sentence
that will help you remember them in order!!**
•Here are the phases: Interphase, Prophase, Metaphase, Anaphase, Telophase &
Cytokinesis
MY sentence: I Picked More Apples Than Carrots
MITOSIS (continued):
PROPHASE:
•In this phase, the nuclear envelope breaks down
•The chromosomes become visible
•The centrioles („scissors‟) begin to move to opposite sides of the cell
•Spindle fibers, which are long strands of protein begin to form
Label the following in the picture:
- Chromosome
- Nuclear envelope
- Centrioles
- Spindle fibers
MITOSIS (continued):
METAPHASE:
•The centrioles are at the poles of the cell
•In this phase, the chromosomes attach to the spindle fibers
•The chromosomes line up in the MIDDLE of the cell
•The spindle fibers will play “tug of war” with the chromosomes
Label the following in the picture:
- Chromosome
- Centrioles
MITOSIS (continued):
ANAPHASE:
•In this phase, the cell gets a little bit longer in shape
•The chromosome will split in half:
•1 chromatid will go to one side of the cell
•the other chromatid will go to the other side of the cell
•Each chromatid is now called a CHROMOSOME!!
Label the following in the picture:
- Chromosome
- Centrioles
- Spindle fibers
MITOSIS (continued):
TELOPHASE:
•In this phase, the chromosomes finish separating
•The spindle fibers break down
•The nuclear envelope comes back
•The chromosomes become LESS VISIBLE
•The 2 cells are ALMOST completely separated
Label the following in the picture:
- Chromosomes
- Nuclear envelope
- Centrioles
2. CYTOKINESIS
•In this phase, the CYTOPLASM (gel) divides
•Now there are 2 identical cells
•These cells are called daughter cells
•Each cell has a total of 46 chromosomes
(Telophase)
Label the following in the
BOTTOM picture:
- Chromatin
- Centrioles
- Nuclear envelope
- Nucleolus
2 Daughter cells
http://www.neok12.com/php/watch.php?v=zX645478027c03150f647502&t=Cell-Division