CHAPTER 5: GENETICS

THEME 2:
MAINTENANCE AND
CONTINUITY OF LIFE

CHAPTER 5
GENETICS

GENETICS

is a study of genes, hereditary
& variations in organisms.

Topic 5 GENETICS

5.1 Cell Division
Pembahagian Sel

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Topic 5 GENETICS

1. Gene, Deoxyribonucleic Acid (DNA)
and Chromosomes

English  Chinese Translation

Cell =细胞
Chromosome =染色体
Deoxyribonucleic acid (DNA) =脱氧核糖核酸
Gene = 基因
Mitosis = 细胞分裂
Meiosis =减数分裂
Daughter cells = new cells =子细胞,新细胞
Parent cells = original cells亲本细胞,要进行分裂的细胞

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Topic 5 GENETICS

Human Cheek Cells人脸细胞

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Topic 5 GENETICS

Sperm Cells and Ovum

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Topic 5 GENETICS

Blood Cells血细胞

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3. Topic 5 GENETICS
4.
5.
1.

2.

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Topic 5 GENETICS

Cell Division

Cell Division – Chromosomes and Genes

Cell membrance Nucleus membrance

Cytoplasm Nucleus

Animal cell

Nucleus of a cell contains many small Gene Gene

tread-like structures called

chromosomes. Part of a DNA
molecule
Chromosomes are made up of uncoiled to
deoxyribonucleic acid (DNA) and protein. show genes

Chromosomes contain hereditary material
called genes.

Gene is heritable characteristic which
passes on hereditary information from
one generation to another. Example hair
colour, appearance, blood group, etc.

A chromosome

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Topic 5 GENETICS

Homologous

One Gene
chromatid

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Topic 5 GENETICS

DNA

Made up of basic units known as nucleotides.

StructureCoellfDniviusiocnleotides

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1. Cell细胞is the basic unit for living things.Topic 5 GENETICS

Cell contains nucleus.
2. Chromosome染色体

- the fine thread-like structures found in
the nucleus of a cell.

3. Deoxyribonucleic acid (DNA)
脱氧核糖核酸

- long molecules containing genes.
4. Gene基因 – an inheritance unit that

determines a characteristic of an
individual.确定个人特征的继承单位

PN NORAZLIN -Science Form 4 2020

Topic 5 GENETICS

Cell Division

解说

每个人类细胞中都有46条染色体,除了精子和
卵子有23条染色体

染色体在细胞核中(nucleus)

染色体由DNA组成

染色体上有很多基因(gene)

基因是DNA的一小部分

每个基因控制不同的特质,例如血型,肤色,头
发类型(直或卷曲)…..

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Topic 5 GENETICS

Cell Division

Nucleus

Chromosomes

DNA

Gene

Relationship Between Chromosome, DNA and Gene

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Topic 5 GENETICS

HUMAN KARYOTYPE

1. Human cell contain 46 chromosomes /
23 pair双chromosomes.

2. The pair of chromosomes knows as
homologous chromosomes.这对染色体
被称为同源染色体。

3. Homologous chromosomes are
arranged according their shape and
size. This arrangement called
karyotype.

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Topic 5 GENETICS

Human Karyotype

Male Karyotype Female Karyotype

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Topic 5 GENETICS

Human Chromosomes

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Topic 5 GENETICS

Autosomes and Sex Chromosomes in Female

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Topic 5 GENETICS

Cell Division

Important for Cell Division

Reproduction

Growth of any organism

Type Of Cell Division

Mitosis细胞分裂
Meiosis减数分裂

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Topic 5 GENETICS

MITOSIS

Mitosis is a cell division process that forms
two identical daughter cells, each having the
same number of chromosomes and genetic

content as the parent cell.

形成两个相同子细胞的细胞分裂过程

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Topic 5 GENETICS

Cell Division

MIMTitOosSisIS

Takes place in somatic cells (body cell) in human and animals.
发生在人和动物的体细胞中
somatic cells=体细胞 (除了精子和卵子

Takes place in the meristematic tissue such as the
tip of the roots and the shoot of the plants.
它也发生在分生组织中，例如根尖和植物的芽
meristematic tissue = 分生组织
（在植物的根部，茎，和芽的细胞，可分裂成其他细胞）

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Topic 5 GENETICS

Cell Division

MITOSIS

Importance of mitosis

Importance of To form new cells for growth.
mitosis
To form new cells to replace damaged or dead cell or
tissues.

To enable hereditary material in parent cell to be
passed on to daughter cell.

To ensure number of chromosomes of daughter cell
same as parent cell.

To enable asexual reproduction such as binary fission.

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Topic 5 GENETICS

Importance of mitosis

1. For growth成长
2. To replace damaged cells更换受损细胞
3. For asexual reproduction无性繁殖

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Topic 5 GENETICS

Importance of mitosis

a. Growth and development

mitosis

b. Replacement of damaged cells

•Allows a multicellular organism to maintain its tissues
which require frequent replacement.
•For example, the skin cells can only live for 2 weeks,
after which new cells are formed through mitosis.

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Topic 5 GENETICS

Importance of mitosis

c. Asexual Reproduction

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Plants Topic 5 GENETICS

Animals & Human

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Topic 5 GENETICS

MITOSIS

Mitosis happens in 4 phases:发生在四个阶段

1)Prophase PMAT

2)Metaphase (Prophase, Metaphase, Anaphase, Telophase)
Pro, Middle, Away, Two
3)Anaphase

4)Telophase

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Topic 5 GENETICS

MITOSIS

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Interphase Topic 5 GENETICS

Stage before the process of mitosis and
meiosis begin.分裂开始之前的休息阶段
At this stage, DNA replication takes place.
DNA复制发生
The shape of a chromosome that resembles
thin thread cannot be seen through a
microscope .染色体类似于细线

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MITOSIS Topic 3 HereTdoiptyicA5ndGEVaNrEiaTtIiConS

Parent cell Nuclear Stages Of Mitosis
Chromosome membrane
Parent cell with two pairs of chromosomes.
Chromatid Centromere Chromosomes in the nucleus shorten, thicken and are
more visible.

Centriole Replication of chromosomes occur. Each chromosome
copies in an extra set of genetic information.
Each chromosome consists of a pair of chromatids
joined by a centromere.

Spindle Spindle threads emerge.
thread Nucleus membrane disappears.

Spindle formation is completed.
Chromosome arrange themselves at the centre
(equator) of the cell.

Chromatids separate at the centromere and are pulled
to the opposite poles of the cell by the spindle threads.

Cell starts to divide.
Nucleus membrane forms again to surround each set of
chromosomes.

Daughter Two daughter cells are formed.
cell Daughter cell has two pairs of chromosomes just like the
parent cell.
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Topic 5: GENETICS

Pembahagian Sel

Sel induk Peringkat-peringkat Mitosis
Kromosom
Membran Sel induk dengan dua pasang kromosom.
Kromatid nukleus Kromosom dalam nukleus menebal, memendek dan
jelas kelihatan.
Sentromer

Sentriol Berlakunya replikasi kromosom. Setiap kromosom
menyalin satu set maklumat genetik.
Setiap kromosom mempunyai sepasang kromatid yang
disambungkan oleh sentromer.

Gentian Gentian gelendong terbentuk.
gelendong Membran nukleus hilang.

Pembentukan gelendong lengkap.
Kromosom tersusun di sepanjang satah khatulistiwa.

Kromatid berpisah di sentromer dan tertarik ke kutub
yang bertentangan oleh gentian gelendong.

Sel anak Sel mula membahagi.
Membran nukleus terbentuk di sekeliling setiap
kumpulan kromosom.

Dua sel anak terhasil.
Setiap sel anak mempunyai dua pasang kromosom
seperti sel induk.

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Prophase (Pro // Permulaan)Topic 5 GENETICS

The chromosomes in the nucleus shorten, thicken and
become clearly visible.细胞核中的染色体变短，变粗并清晰
可见
Each chromosome consists of two chromatids joined at
the centromere.每个染色体由在着丝粒处连接的两个染色单
体组成
Spindle fibres begin to form.
Nuclear membrane and nucleolus disintegrate (to
become weaker or be destroyed by breaking into small
pieces)

PN NORAZLIN -Science Form 4 2020

Metaphase (Middle // Menyusun)Topic5 GENETICS

Chromosomes are arranged at the
equatorial plane.染色体排列在赤道平面
They are attached to spindle fibres which
are connected to the poles.它们连接到纺锤
纤维，纺锤纤维连接到极

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Anaphase (Away // Asing)Topic 5 GENETICS

The centromere splits into two.着丝粒一分为
二
Each chromatid separates and moves
towards the opposite poles of the cell.每个染色
单体分离并向着细胞的相反两极移动

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Telophase (Two // Terbahagi dua)Topic5 GENETICS

Chromatids reach the opposite poles.染色单
体到达相反的两极
Nuclear membrane and nucleolus are
formed again.再次形成核膜和核仁

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Topic 5 GENETICS

Cytoplasm divides.
(Cytokinesis process)

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Topic 5 GENETICS

Two identical daughter cells (new
cells) are formed.形成两个相同的子细
胞 with the same number of
chromosomes and genetic information
as the parent cell are formed (diploid,
2n- 46 chromosomes).

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Topic 5 GENETICS

Meiosis

Meiosis is a process where the cell
divides into four distinct cells, each

containing half the number of
chromosomes in the parent cell.

一个细胞分为四个不同细胞的过程

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Topic 5 GENETICS

Cell Division

Meiosis

 Takes place in reproductive organs生殖器官

 Meiosis in human takes place in the testes（睾丸）（testis） and the ovary
（卵巢）

 In plants, meiosis takes place in the anther and the ovary.

To produce gametes(卵子和精子) for sexual reproduction.

Importance of To produce variation among species of the same
meiosis organism.

Crossing over occurs where chromatics overlaps with one
another and exchange of genetic material takes place.

To ensure number of chromosomes in the zygote is diploid
(2n) same as their parent when sperm fuses with ovum
during fertilisation.

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Topic 5 GENETICS

In human ,meiosis takes place in reproductive organs; male’s
testes and the female’s ovary.

.

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Topic 5 GENETICS

In plants, meiosis takes place in the anther and the ovary.

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Topic 5 GENETICS

Importance of meiosis

a) Formation of gametes (sperm and ovum)

b) To maintain the number of chromosomes
after fertilisation维持受精后的染色体数

c) Crossing over is important in meiosis to
produce variation among offspring交叉在减数
分裂中产生子代变异很重要

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Topic 5 GENETICS

Variation in offspring

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Topic 5 GENETICS
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Topic 5 GENETICS

Meiosis

Can be divided into:可以分为
Prophase I
Metaphase I
Anaphase I
Telophase I

Cell divides into two, then continue:
分为两部分，然后继续
Prophase II
Metaphase II
Anaphase II
Telophase II

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Parent Cell Division Topic 5 GENETICS
cell Stages Of Meiosis
Meiosis involves two stages of
Chromosome cell division.
Centromere
Parent cell with two pairs of chromosomes.
Meiosis I Chromosomes shorten and thicken.

Meiosis II Replication of chromosomes occur.
Each chromosome consists of two chromatids joined by a centromere.

Homologous chromosomes pair up.
Crossing-over occurs on chromatids.
Exchange of genetic material takes place.
Nuclear membrane disappears.

Chromosomes arrange themselves in equator of the cell.
Homologous chromosome separates and moves to the opposite pole

of cells.

Cell begins to divide. Nuclear membrane reforms.

Two daughter cells are produced.

Chromosomes arrange themselves in the equator of new cell.
Nuclear membrane disappear.

Chromatid separates and moves to the opposite pole of the cells.
Chromatid now becomes chromosome.

Cell begins to divide.
Nuclear membrane reforms again.

Four daughter cells are formed.
Each daughter cell has different genetic information.

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Topic 5 GENETICS

Sel Pembahagian Sel
induk
Kromosom Peringkat-peringkat Meiosis Meiosis melibatkan dua peringkat
Sentromer pembahagian sel.
Meiosis I
Sel induk dengan dua pasang kromosom.
Meiosis II Kromosom memendek dan menebal.

Berlakunya replikasi kromosom.
Setiap kromosom terdiri daripada dua kromatid yang disambungkan

oleh sentromer.

Pemasangan kromosom homolog.

Pindah silang berlaku di kromatid.
Pertukaran bahan genetik.
Membran nukleus hilang.

Kromosom tersusun di satah khatulistiwa.
Kromosom homolog berpisah dan bergerak ke kutub bertentangan.

Sel mula membahagi. Membran nukleus membentuk semula.
Dua sel anak dihasilkan.

Kromosom tersusun di satah khatulistiwa.
Membran nukleus hilang.

Kromatid berpisah dan bergerak ke kutub bertentangan.
Kromatid bertukar menjadi kromosom.

Sel mula membahagi.
Membran nukleus membentuk semula.

Empat sel anak terhasil.
Setiap sel anak membawa maklumat genetik yang berbeza.

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Topic 5 GENETICS

Meiosis I

Can be divided into:可以分为

Prophase I
Metaphase I
Anaphase I
Telophase I

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Prophase I (Pro // Permulaan)Topic 5 GENETICS

• Chromosomes in the nucleus shorten , thicken and
become clearly visible.

• Homologous chromosomes pair together.同源染色体
配对在一起

• Crossing over occurs.发生交叉

• Crossing over = exchanging of genetic materials, will produce
new cells which are different from each other and also
different from the parent cells遗传物质交换,会产生彼此不
同并且也与亲代细胞不同的新细胞

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Metaphase I (Middle // Menyusun)Topic5 GENETICS

• Chromosomes are arranged in an equatorial
plane.染色体排列在赤道平面内。

• The spindle fibres are attached to the
centromere.

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