04/20/23 1

Today’s Agenda:Journal Question : What is a chromosome?*1. Lecture: Introduction to Chromosomes, Mitosis & Meiosis (slide 47)2. Packet for Unit (Bring to class every period) (Buy Color Pencils & Glue Stick)3. Today’s Focus: DNA Characteristics & Chromosome Structure4. Color first picture in packet: DNA: The Double Helix.5. Video: Genetics6. Exam before break

04/20/23 2

Cellular Reproduction

Dr. Rick Woodward

04/20/23 3

DNA Characteristics

A. Long thin molecule (double helix) that stores genetic information (Unit of Heredity) “Blueprint for Life”

B. Location: Nucleus of the Cell

04/20/23 4

DNA Characteristics

C. Function: Controls & Directs Activities of the Cell

D. In humans there are 6 billion pairs of nucleotides

- If a cell were the size of a basketball, the DNA would stretch for 40 miles!

04/20/23 5

Chromosome StructureA. DNA is coiled into very

compact structures called chromosomes.

B. Chromosomes are rod-shaped structures of DNA & Protein.

04/20/23 6

Chromosome StructureC. A histone is a protein molecule

that DNA wraps around during chromosome formation.

04/20/23 7

Anatomy of a Chromosome

04/20/23 8

Chromosome Number

A. Each species has a specific number of chromosomes in each cell.

B. For each chromosome there are two copies or one pair (total):

(1) one from the mother

(2) one from father

04/20/23 9

Chromosome NumberC. Humans have 46

chromosomes (23 pairs)

D. Gorillas have 48 chromosomes (24 pairs)

E. Your neighbor’s cat has 32 chromosomes (16 pairs)

04/20/23 10

Genetically Engineered Cats

1. Some day these cats may rule the planet with the assistance of militant cows.

2. What you are about see is classified top secret by the federal government.

04/20/23 11

Genetically Modified Cats Martial Arts Super Cats

04/20/23 12

Extreme Kung Fu Cat

04/20/23 13

Bi-Pedal Snow Cat Dodging a Bullet

04/20/23 14

Karaoke Cats Transmitting Code

04/20/23 15

Gaming Nintendo Wii CatGenetically superior gaming skills

04/20/23 16

Laser Cats

04/20/23 17

Diabolical Joker Cat

04/20/23 18

What is a Chromatid?A. It is one of two identical

parts of a chromosome

04/20/23 19

What is a Centromere?

A. Each chromosome has a central constricted region called a centromere that serves as an attachment point.

What is a telomere?A. The telomeres protect the

tips of the chromosomes from damage.

04/20/23 20

04/20/23 21

04/20/23 22

Sex Chromosomes

A. Determines the sex of an organism.

B. In humans:

XX = female

XY = male

04/20/23 23

Autosomes A. An autosome is a chromosome

that is not a sex chromosome.

04/20/23 24

Karyotype: A Picture of an Individual’s Chromosomes

04/20/23 25

Homologous ChromosomesA. Every cell of an organism produced

by sexual reproduction has two copies of each autosome.

04/20/23 26

Homologous Chromosomes

B. We get one copy of each autosome from each parent.

C. Two copies of each chromosome are called homologous pairs of chromosomes.

04/20/23 27

04/20/23 28

*Haploid (1n) vs. Diploid (2n) CellsA. Haploid Cells (1n)

(1) One set of chromosomes

(2) Sperm cells

(3) Egg cells

B. Diploid Cells (2n)

(1) Two sets of chromosomes

(2) All non-reproductive cells.

(3) Zygote/Fertilized Egg

C. Red blood cells do not have any chromosomes because they are missing a nucleus

04/20/23 29

Prokaryote vs. EukaryoteA. Prokaryotes lack membrane-

bound organelles.

1. Bacteria

B. Eukaryotes have membrane-bound organelles (mitochondria, nucleus, etc.)

1. Plants & Animals

04/20/23 30

Cell Division in Prokaryotes

BINARY FISSION is the division of a prokaryotic cell (bacteria) into two identical cells!

1. DNA copied

2. Cell begins to divide

3. Two identical haploid cells.

04/20/23 31

CELL DIVISION IN EUKARYOTES Both the cytoplasm and the

nucleus divide. Two types:

1. MITOSIS (clones)

A. Reproduction of unicellular organisms

B. Addition of cells to a tissue or organ.

2. MEIOSIS (gametes/sex cells)

A. 1/2 the chromosome number

B. Cells recombine in sexual reproduction.

04/20/23 32

DNA Replication

The DNA must be copied and then divided exactly so that each cell gets an identical copy.

04/20/23 33

Cellular Reproduction (Mitosis)

A. Growth is the result of a cell’s ability to reproduce itself.

04/20/23 34

Cellular Reproduction (Mitosis)

(1) New body cells are produced from other, already existing cells; when one cell becomes two.

(Recall “The Cell Theory”)

04/20/23 35

Cellular Reproduction (Mitosis)

(2) Examples: Skin cells, intestinal tracts cells are continuously being replaced.

04/20/23 36

Cellular Reproduction (Mitosis) B. New cells are produced

that contain the same genetic information as the cells from which they came.

04/20/23 37

Cellular ReproductionC. Mitosis = The process that

produces and replaces body cells; exact copies.

(i.e. skin cells)

1. Continuance of an individual’s growth throughout life.

04/20/23 38

Cellular ReproductionD. Meiosis = The process that

produces reproductive cells needed for the formation of new individuals.

1. Continuance of the species.

04/20/23 39

Cellular Reproduction

I. Life from Life = Cells from Cells

A. Disproving Spontaneous Generation:

(1668, Francesco Redi’s controlled experiment showed that maggots do not spontaneously generate from decaying meat.)

04/20/23 40

04/20/23 41

Cellular Reproduction B. Louis Pasteur disproved the theory

that microorganisms are not spontaneously generated from air.

1. Used a flask with a long S-shaped neck, boiled broth.

2. Pasteurization is the partial sterilization of a substance by increasing the temperature of that substance to destroy objectionable organisms (i.e. bacteria).

04/20/23 42

Cellular Reproduction C. Reproduction of Body Cells (Mitosis)

1. Cell reproduction occurs when parent cells divide.

A. Two new daughter cells arise from each parent cell.

04/20/23 43

Cellular ReproductionB. After reaching full

development, an organism needs new cells to:

(1) repair damaged tissue, replace cells that are lost from outer surfaces (skin cells) and resist disease.

04/20/23 44

Cellular Reproduction

C. It is estimated that 25 million cell divisions occur every second in the adult human body.

04/20/23 45

Cellular Reproduction

D. Rapid cell division or cell growth that is out of control is called cancer.

1. Suffix: -oma

04/20/23 46

Looking at Cancer Cells

04/20/23 47

The Cell Cycle

04/20/23 48

Cellular Reproduction

2. The Cell Cycle

(Interphase + Mitosis = The Cell Cycle)

“Interphase”

(1) Interphase (non-reproducing stage that follows when cell reproduction/replication is complete)

04/20/23 49

Today’s Agenda

Today’s Agenda:

Journal Questions:

a. What are the parts of the cell cycle?

b. What is the difference between mitosis and meiosis?

*1. Lecture: Cellular Reproduction & The Stages of Mitosis (Slide 91)

2. Work on packet: Karyotype Activity

3. Homework: Finish packet and study

4. Exam this Thursday (12/16/10)

04/20/23 50

Cellular Reproduction(2) DNA Synthesis & Duplication

occur during Interphase.

04/20/23 51

Cellular Reproduction2. The Cell Cycle continued…

A. The cell spends most of its life in interphase.

B. Chromatin is present in the nucleus during interphase.

C. Midway through interphase each chromosome and the

DNA it contains replicates.

04/20/23 52

Mitosis

Mitosis = Division of nuclear material

a. There are four stages

b. Mitosis occurs in most of the cells in Eukaryotes.

P.M.A.T.

Please make another taco.

Prophase, Metaphase, Anaphase, Telophase

04/20/23 53

Vocabulary-Centromere = region where two

chromatids join

-Chromatid = Either of two strands that together form a chromosome.

-Gamete = Sex Cell (Sperm or Egg)

04/20/23 54

Anatomy of a Chromosome

Anatomy of a Chromosome

A. The telomeres protect the tips of the chromosomes from damage.

04/20/23 55

Anatomy of a ChromosomeA histone is a protein molecule that

DNA wraps around during chromosome formation.

04/20/23 56

04/20/23 57

Vocabulary

-Cell plate = forms the plasma membrane between two new plant cells.

-Spindle (shown in green) = Structure located between the centrioles of a cell.

04/20/23 58

The Four Stages of Mitosis(1) Prophase (first stage of mitosis)

A. Chromosomes condense and organize: nuclear membranes and nucleoli disappear; spindle apparatus assemble and attach to centromeres of duplicated chromosomes.

-Each strand is a replica of the other and is called a chromatid.

04/20/23 59

The Four Stages of Mitosis(2) Metaphase (second stage of

mitosis)

A. Spindles line up duplicated chromosomes along the equator (middle) of the cell, one spindle to each half or chromatid of the duplicated chromosome.

04/20/23 60

The Four Stages of Mitosis(3) Anaphase (third stage of mitosis)

A. The centromere of each duplicated chromosome is separated and paired chromatids are pulled apart.

04/20/23 61

The Four Stages of Mitosis

(4) Telophase (Forth stage of mitosis)

A. Chromosomes uncoil: nucleoli reappear, cytokinesis

(Cyto = cell, Kine = movement) occurs and genetically identical daughter cells are produced.

-(In animal cells, the plasma

membrane pinches in.)

-(In most plants, a cell plate begins to appear.)

04/20/23 62

04/20/23 63

Cytokinesis

04/20/23 64

Summary of Mitosis Prophase:

Chromosomes condense Nuclear envelope disappears centrosomes move to opposite sides of the cell Spindle forms and attaches to centromeres on

the chromosomes

Metaphase Chromosomes lined up on equator of spindle centrosomes at opposite ends of cell

Anaphase Centromeres divide: each 2-chromatid

chromosome becomes two 1-chromatid chromosomes

Chromosomes pulled to opposite poles by the spindle

Telophase Chromosomes de-condense Nuclear envelope reappears Cytokinesis: the cytoplasm is divided into 2 cells

04/20/23 65

Mitosis Review

04/20/23 66

Control of the Cell Cycle A. Rate of Cell Division

1. Different types of cells divide at different rates.

2. Bone marrow cells reproduce rapidly to form new red blood cells.

-Red Blood Cells are replaced every 120 days.

04/20/23 67

Control of the Cell Cycle 3. Nerve and muscle cells

never reproduce once they mature.

04/20/23 68

Control of the Cell Cycle

4. If one kind of cell begins to reproduce too rapidly, cancer develops.

(a) Malignant Cancers are deadly.

(b) Benign Cancers are not usually deadly.

04/20/23 69

Regulation of the Cell Cycle

A. Most normal cells will divide repeatedly until they come in contact with another cell.

04/20/23 70

Regulation of the Cell Cycle B. When cells stop dividing, they

always stop at the same point in the cell cycle –just before DNA replication begins in interphase.

04/20/23 71

Regulation of the Cell Cycle

C. Control proteins have been discovered that can activate mitosis.

04/20/23 72

Meiosis (Sexual Reproduction)

A. Meiosis – Reduces the chromosome number by half and results in new genetic combinations in the gametes.

04/20/23 73

Meiosis (Sexual Reproduction)

B. This process of cell division is involved in sexual reproduction.

(1) Recall: Mitosis is for cellular reproduction

04/20/23 74

Meiosis (Sexual Reproduction)C. In animals meiosis often results in two

gametes: haploid egg (1n) cells and haploid sperm cells (1n).

(1) Sperm (n) + Egg (n) =

Zygote/Fertilized Egg (diploid/2n)

(2) Zygote develops into a new organism.

(3) Meiosis and fertilization are important processes because they result in genetic variation.

04/20/23 75

Meiosis (Sexual Reproduction)D. In meiosis two nuclear divisions

take place (Meiosis I, Meiosis II) instead of one as in mitosis.

04/20/23 76

Meiosis (Sexual Reproduction) E. Meiosis I, like mitosis,

follows a period of interphase.

04/20/23 77

Meiosis (Sexual Reproduction)F. Meiosis II occurs in each cell

formed during Meiosis I.

04/20/23 78

Production of Reproductive Cells Chromosome Numbers & Characters

A. Diploid Cells

1. Animal Cells – Chromosomes come in pairs.

2. Simple Plant Cells – Do not have paired chromosomes (i.e. moss, fungi)

04/20/23 79

Production of Reproductive Cells (Meiosis)

Chromosome Numbers & Characters

3. Complex Plants have paired chromosomes.

(i.e. carrots, cabbages, oak trees)

04/20/23 80

Production of Reproductive Cells (Meiosis)

Chromosome Numbers & Characters

4. Human Cells have 23 pairs of chromosomes; a fruit fly cell’s contain four pairs of chromosomes.

04/20/23 81

Cell Reproduction in Prokaryotes

A. Cell reproduction in prokaryotes (bacteria) is through binary fission.

B. Each new cell receives a copy of the single chromosome.

C. Prokaryotes have a single chromosome (no protein spools)

04/20/23 82

Steps of Binary Fission in BacteriaSee Packet (p.39)

1. The single chromosome is attached to the inside of the cell membrane.

2. A duplicate chromosome is formed.

3. The new chromosome attaches to the cell membrane.

4. Growth of new cell membrane and cell wall material separates the two copies of the chromosome and elongates the cell.

04/20/23 83

Steps of Binary Fission in Bacteria

5. More new membrane and cell wall form and push inward at the midpoint of the length of the cell.

6. The two chromosomes become separated.

7. Two separate daughter cells are produced.

04/20/23 84

Cellular Reproduction

“Answers to first page of packet” p.37

Many early scientists performed faulty experiments that convinced them that (1) nonliving things could give rise to living things. This idea is called (2) spontaneous generation.

04/20/23 85

Cellular Reproduction

In 1668, (3) Francisco Redi disproved this theory. However, in 1675, the world of (4) microorganisms was discovered, reopening the split between scientists over spontaneous generation.

04/20/23 86

Cellular Reproduction

An experiment performed by (5) Louis Pasteur in 1864 ended the debate. At the time, (6) air was believed to be necessary for spontaneous generation. Pasteur proved that microorganisms are not spontaneously generated.

04/20/23 87

Cellular Reproduction

This work led to the theory of (7) biogenesis, which stated that all organisms are produced from other (8) organisms. This tied in with the (9) cell theory, formulated about the same time. By the late 19th century, scientists worked with these two theories that indicated that all life must come from (10) life.

04/20/23 88

Cellular Reproduction

11. Early in the organism’s development, the cells contribute to overall growth. Later, new cells are needed to repair damaged tissues, replace lost cells, and resist disease.

04/20/23 89

Cellular Reproduction

12. What would happen to a cell if it continued to grow unchecked?

The surface area of the plasma membrane would not be large enough to meet the cell’s needs. The cell would stare or become poisoned.

04/20/23 90

Cellular Reproduction

13. Replication is the process of making an exact copy. It provides the cell with a second set of chromosomes for reproduction.

14. Interphase and mitosis make up the cell cycle.

Work on the Karyotype in your packet1. Cut out chromosomes.

2. Arrange into homologous pairs.

3. Tall to Small, Number 1-23 pairs:

(Recall 1-22 = Autosomes)

(23 = Sex Chromosomes)

4. Glue into your composition book.

04/20/23 91

Today’s AgendaJournal Question: What is a karyotype?

1. Study guide for Exam V – Answer questions 1-37.

2. Finish your karyotype.

3. Finish your packet.

4. Micro-slide viewer lab

5. Homework: Study, Complete all of your work.

6. Your Test is on Friday/Everything is due

04/20/23 92

04/20/23 93

Pay Attention!1. Micro-slide viewer activity first!

a. Plant Mitosis Slide

b. Meiosis Slide

04/20/23 94

Today’s Lab Questions:Write down questions 1-8 in your composition book

1. What is the difference between mitosis, meiosis, and binary fission?

2. What do homologous pairs of chromosomes refer to?

3. Label the parts of a chromosome: Chromatid, Centromere, Gene

4. How many pairs of chromosomes do human’s have?

5. What does XX = ________ and XY = __________

6. What is a karyotype?

7. What is the function of a spindle fiber? What is a tetrad?

8. Diagram a picture of the Cell Cycle. Include: G1, S, G2, M

04/20/23 95

Today’ s Cell Cycle Lab

1. Carefully read all instructions on today’s laboratory handout (which is in your unit packet).

2. Diagram/Draw all phases on the cell cycle in your composition book.

3. List two facts for each phase.

4. Answer questions 1-8 from the laboratory handout in your composition book.

5. Start studying tonight for your exam.

04/20/23 96

Different Stages of the Cell Cycle (Onion Root Tip): Today’s Lab