Chapter 5 (teacher)

Biology Teaching and Learning Module Cell Division

Chapter 5 : Cell Division(ANSWERS)

Theme : Investigating Cell As a Basic Unit of Life

LS Understanding Mitosis

5.1.1 The necessity for the production of new cells in organisms

List down the need for producing new cells in life (significance of mitosis)

1. produces new cells for growth2. repair and replaces cells that are dead or damage.3. to increase the number of unicellular organisms4. ensure that the offspring/new cells are genetically identical to the parent5. mitosis preserves the diploid number of chromosomes

5.1.2 The necessity for the production of new cells identical to parent cells

List down the necessity for the production of new cell identical to parent cells

1. Species survival2. preserve the diploid number of chromosomes3. preserve the genetic information 4. to preserve the parent characteristics

5.1.3 Definition of Mitosis

A type of cell division which involves the division of the nucleus to produce two daughter cells, each contain same number and same kind of chromosomes as the parent cells.

Operational-definition – based on observationThe produce of two daughter cells which is a look like the parent cell with the division of nucleus

Places where the mitosis occur during the division of cell - all somatic (in animal) cells which are all body cells except gametes- meristem cells ( in plant) at the end of the shoots, the end of roots and cambium

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5.1.4 The cell cycle

The cell cycle is the period that extends from the time a new cell is produced until the time the cell completes a cell division. The cell cycle can be divided into two major phases : interphase and mitotic cell division or the M phase. Mitotic cell division consists of mitosis (nucleus division) and cytokinensis (cytoplasmic division)

On the cell cycle diagram below, identify the phases and explain what happen during each phase.

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(G2) Fasa 2 : Tenaga dihasilkan

(S) Synthesis phase : DNA replication occur

(1) Phase 1 : Organelle are synthesized and biochemical substances (enzymes) are produced

(M) Mitosis

(G2) Phase 2 : Energy is produced


5.1.5 Mitosis Process

Mitosis involved of division of nucleus from the parent cell to produced two new daughter cells which are genetically identical to the parent. Before mitosis occur cell is in the interphase level and after mitosis the cytokinesis occur.

Cell cycle = Interphase + Mitosis + Cytokinesis

Activity 1 : Watching the animation phases in mitosisActivity 2 : Identify phases of mitosis

On the diagram below, identify phases of mitosis which have been labeled

K : Early prophase

L : Metaphase

M : Interphase

N : Late telophase

O : Early anaphase

P : Late anaphase

Q : Late prophase

R : Early telophase

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Activity 3 : Arrange the various stages of mitosis in the correct sequence and explain the mitosis and cytokinesis

Stages of cell division of mitosis process.

Instruction : Cut the phases of division cell of mitosis above and paste the appropriate pictures in the box provided in the next page in correct order. Explain what happen during each stage in the boxes provided.

Anaphase

Interfasa

Metaphase

Prophase Metaphase

Late TelophaseEarly Telophase

Anaphase

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Stages of cell division of mitosis process.

Diagram Explanation

Interphase

The chromosomes are not visible but appear as thread-like structures called chromatin

Nucleus is large and prominent

Involves synthesis of protein and organelles, replication of DNA,

Prophase

Chromosomes in the nucleus condense and become more tightly coiled. The chromosomes appear shorter and thicker and are visible.

Each chromosome now consists of a pair of sister chromatids joined together at the centromere.

The spindle fibres begin to form and extend between the centrioles.

The chromatids are attached to the spindle fibres by their centrioles

At the end of the prophase, the nucleolus disappears and the nuclear membrane disintegrate.

Metaphase

Begins when the centromeres of all chromosomes are lined up on the metaphase plate.

Ends when the centromeres divide

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Diagram Explanation

AnaphaseTwo sister chromatids of each chromosome separate at the centromere.

The sister chromatids are pulled apart to the opposite poles by the shortening of the spindle fibres

Once separated, the chromatids are referred to as daughter chromosomes

By the end of anaphase, the two poles of the cell have complete and equivalent sets of chromosomes

Early Telophase

Begin when the two sets of chromosomes reach the opposite poles of the cell.

The chromosomes start to uncoil and revert to their extended state (chromatin).

The chromosomes become less visible under the microscope.

Late Telophase

The spindle fibres disappear and a new nuclear membrane forms around each set of chromosomes

The nucleolus also re-forms in each nucleus.

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Cytokinesis is the division of the cytoplasm. In animal cell a cleavage furrow is formed while in plant cell a cell plate is formed.

Explain the cytokinesis process in the table below.

Diagram ExplanationAnimal cell

In animal cell, actin filaments in the cytoplasm contracts to pull a ring of plasma membrane inwards

Forming a groove called a cleavage furrow

Plant cell

In plant cell, membrane-enclosed vesicles gather at a plant cell’s equator between the two nuclei

The vesicles fuse to form a cell plate.

The cell plate grows outwards until its edges with the plasma membrane of the parent cell.

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5.1.6 Application of Knowledge on Mitosis

Activity : Collect information. Do an article about the application of knowledge mitosis according to the topic below. In your article you can include tabled data, picture and other suitable technique which is necessary.

a) Tissue culture

Diagram

Explanation

1. Wash the tomato plant tissue with hypochloric solution.2. Tomato tissue are cultured in a sterile medium rich in nutrients3. After the callus is formed, transfer the tissue culture to a new sterile medium rich in nutrients

which contain growth hormone.4. After the shoots is formed, transfer them into the plant pod

Tomato plant tissue

Callus

root

Shoots

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b) Cloning : Advantages and Disadvantages

Advantages Disadvantages

Ensure the continuity of hereditary traits from the parent to the clones.

Increase the rate of production and the quality of the products

Good qualities of the plants and animals can be selected and maintained in the clones

Many clones are produced in a short time Can be carried out any time of the year.

The resistance of the clones towards diseases and pests is the same. If a clone is infected with a disease or attacked by pests then all the clones will also affected and die.

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5.1.7 The Importance of Controlled Mitosis

Explain the importance of controlled mitosis.

1. mitosis – increase the number of cells and repair damage cells. It happens in animal and plant in growth, preserve the normal body tissues for survival of life.

2. meiosis – produce haploid gametes to maintain the number of chromosomes in organisms

5.1.8 The Affect of Uncontrolled mitosis in living things

Explain the affect of uncontrolled mitosis (cancer)

1. Mitosis occur because the changes of gene which control the cell cycle. 2. This condition happen because of certain virus, toxic chemical substances, expose to the

direct and strong ultra violate rays.3. The cells divide very fast and unregulated. This abnormal cell are called tumour.

Benign tumour – abnormal cells remain at the original site. Do not cause serious problems and can be removed by surgery.Malignant tumour – the tumour becomes invasive and spread to neighbouring tissues. This is cancer.

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Biology Teaching and Learning Module Cell Division LS 2 : Understanding Meiosis

5.2.1 Inheritance in offspring

Process of producing new individuals is celled sexual reproduction. Sexual reproduction involved two parents male and female. Male and female produce

gametes. Each gamete has half the number of chromosome compare to the parent. Gamete is produced during meiosis process.

Male gamete (haploid) and female gamete (haploid) will combined to form a zygote (diploid) and grow to form a new individual.

The new individual which is produced will inherit the characteristic from both parents. The number of chromosomes diploid must be maintained from one generation to another

generation so that the characteristic of the species and the number of chromosome can be maintained. Any changes regarding the number of chromosome will effect the healthy growth (syndrome)

Each species has different number of chromosomes diploid.

5.2.2 Definition of Meiosis

Meiosis is the process of nuclear division that reduces the number of chromosomes in new cells to half the number of chromosomes in the parent cell and produce four daughter cell.

Places where the meiosis occur :In the testes (male) –produce sperms and ovaries (female) – produce ovumAnther of flowers – produce male gamete in pollen and ovaries of the flowers – produce egg cell as ovules

5.2.3 The Stages of Meiosis

Meiosis consist of two separate divisions. They are Meiosis I and Meiosis II.Each stage include the prophase, metaphase, anaphase and telophase.

Activity 1: Arrange the stages of meiosis process and explain each stage.

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Stages of Meiosis Process.

Instruction : Cut the phases of division cell of mitosis above and paste the appropriate pictures in the box provided in the next page in correct order. Explain what happen during each stage in the boxes provided.

Metaphase I

Anaphase II Metaphase II Telophase II

Prophase I

Late Prophase I

Anaphase I

Prophase II

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Biology Teaching and Learning Module Cell Division The Stages of Meiosis Process

MEIOSIS I

Figure Explanation

Early Prophase I

Late Prophase I

Chromosomes begin to condense and shorterHomologous chromosomes come together to form bivalents through a process called synapsis.

Non-sister chromatids exchange segments of DNA in a process known as crossing over.

The points at which segments of chromatids cross over are called chiasmata

Nucleolus and nuclear membrane disappear

Centrioles migrate to the opposite poles of the cells

Spindle fibres strate to form.

Matephase I

The homologous chromosomes are lined up side by side on the metaphase plate.

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Figure Explanation

Anaphase I

Homologous chromosomes move to the opposite poles of the cell.

Telophase IChromosomes arrive at the poles

Each pole now has haploid daughter nucleus because it contains only one set of chromosomes.

Spindle fibres disappear

Nuclear membrane nucleolus reappears

MEIOSIS II

Prophase II

Nuclear membranes of the daughter cells disintegrate again.

The spindle fibres reform in each daughter cell.

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Figure Explanation

Metaphase II

Chromosomes are lined up on the metaphase plate

Anaphase II

The centromeres of the sister chromatids finally separated and move towards the opposite poles of the cell.

Telophase IIThe nucleoli and nuclear membranes re-form

The spindle fibres disappear

Cytokinesis occur and four haploid daughter cells are formed

Each contain half the number of chromosomes and it genetically different from the parent diploid cell.

It will develop into gametes

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5.2.4 Comparison Between Meiosis I and Meiosis II

Complete the table below regarding the similarities and differences between Meiosis I and Meiosis II.

Stage Meiosis I Melosis IIProphase

Similarities :- Spindle fibres are formed- End when chromosomes reach the metaphase plate.

Differences :- Synapsis occur- Crossing over occur

MetaphaseSimilarities :

- Chromosomes are lined up on the metaphase plate

Differences :- Homologous

chromosomes are lined up on the metaphase plate.

Differences :- Chromosomes are lined up

on the metaphase plate.

Anaphase Similarities :- Chromosomes / chromatids move to the opposite poles started

with the centromere

Difference - Paired homologous

chromosomes separate and move to the opposite poles.

- No separation of centromere

Difference - Separation of chromatids - Have separation of

centromere

Telophase Similarities - Nuclear membrane appear

Difference - The chromosomes of

daughter cell are double helix bond

- Two daughter cells are formed

Difference :- The chromosomes of

daughter cell are single helix bond

- Four daughter cells are formed

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5.2.5 Comparison Between Mitosis and Meiosis

- Occur in M phase in cell cycle- The division involved nucleus and cytoplsm

For growth, maintenance and repair of body tissue

Somatic cell

No cross over

Daugther cells are genetically identical to the parent

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Synapsis occur

Has same number of chromosomes as the parent cell (diploid)

Has half the number of chromosomes of the parent cell (haploid)

Synapsis occur

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Daugther cells are genetically non-identical to the parent

Cross over occur

Produce gamete

Reproductive organ

Similarities

Differences

Place occur

The role of cell division

Crossing over happen or not ?

Genetic composition of daugther cells

Number of daugther cell

Synapsis of homologous chromosomes

Number of chromosomes in daugther cells

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5.2.6 The movement of Chromosomes during Mitosis and Meiosis

a) Why the movement of chromosomes during mitosis and meiosis should be regulated in a precise manner?

1. Meiosis – to ensure gametes are haploid and each gametes genetically different from each other

2. Mitosis – to ensure daughter cells has the same number of chromosomes as the parent cell.

b) There are many substances which can interrupt the movement of chromosomes during mitosis and meiosis. Name the substances and the effect of the process

Substances which can interrupt the movement of chromosomes 1. Radioactive rays 2. X rays3. UV rays4. Carcinogens

Affect 1. Cause gene mutation – cancer 2. homologous chromosomes fail to separate – produce abnormal chromosomes

c) How can we avoid the interruption of movement of chromosomes during mitosis and meiosis.

1. Healthy way of life – not smoking 2. Have a balanced diet 3. Practise healthy social activities4. avoid exposure to carcinogenic substances

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Education

Chapter 5 (teacher)