Sains Form 4 Chapter 3

8/17/2019 Sains Form 4 Chapter 3

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CHAPTER 3

Heredity

and

Variation


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Human CellsChromosom

es

DNAGenesCharacterist

ics/ traits

Built up of containing

determiningcontaining

containing


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3.1 CELL DIVISION

• Chromosomes, genes and DNA

• Life cycle and cell division –

Mitosis gro!th – Meiosis se"ual reproduction

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,and DNA

Ci# $my

N&CL$&'

CH()M)')M$'*threadli#e structure

*human +eings have - .0pairs

*contain protein and DNA

DNA- Dou+le heli" structure- *Made up of series of

genes

G$N$- 'egment of DNA

*Genetic codes !hichdetermine an organism

characteristics


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!itosis

• De"nition#

A cell division process in !hich aparent cell .original cell1 di$idesinto t%o identi&a' daughter cells.ne! cells1

• O&&(rs in – Human and animal somatic cells

– 2lants tips of roots and shoots


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p//youtu+e3co/!atch4v5n2G-67(8o7

http://youtube.co/watch?v=nPG6480RQo0http://youtube.co/watch?v=nPG6480RQo0


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Staes o) mitosis

• Chromosomes in the nucleusshorten, thic#en and more

visi+le3

• (eplication of chromosomes

occur3•$ach strand of chromosome iscalled chromatid3

&hromatid

&entromere

n(&'e(s mem*rane


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• 9he nucleus mem+rane forms

again3• 9!o daughter cells are formed3

• $ach daughter cell has the same

num+er of the chromosomes as theparent cell3

• 'pindle :+res emerge3• Chromosomes align themselves in

the centre of the cell3•

9he nucleus mem+rane disappears3

• Chromatids divide and separate to

the opposite ends of the cell3• At the same time the cell starts to

divide3

s+ind'e "*res


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or

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The Im+ortan&e o)!itosis

2roduce ne! cells for

ro%th ? unicellular@ygote to

multicellular organism

Ase(a' re+rod(&tionfor simple organism

li#e amoe+a

Reenerate *odyparts such as li@ard

gro!s a ne! tail

Veetati$ere+rod(&tion such as

rhi@omes, tu+ers,

leaves

2roduce ne! cells forre+'a&in dead&e''s-re+airin

tiss(es


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!eiosis•

De"nition#A process in !hich a nucleus of a parent cell

di$ides into )o(r da(hter &e''s throught!o divisions3

• 9he daughter cells !ill have ha') the n(m*erof chromosomes in parent cell3

• )ccurs in re+rod(&ti$e orans to +rod(&eametes o$(m and s+erms/# – Human and animals testes .male1 and ovary

.female1

– 2lants anthers and ovaries


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p//youtu+e3co/!atch4v5D=*m8'=7

http://youtube.co/watch?v=D1_-mQS_FZ0http://youtube.co/watch?v=D1_-mQS_FZ0


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Staes O) !eiosis # !eiosis 1 And !eiosis 0

• Chromosomes in thenucleus shorten, thic#en

and more visi+le3

• Crossing over and

replication process occuron chromatids3

Meosis 1


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• Chromosomes alignthemselves in the centre of the

cell3• 9he nucleus mem+rane

disappears3

• Chromatids separate and

move to the opposite ends ofthe cell3• 9he cell +egins to divide into

t!o3

• 9!o daughter cells areproduced3

• 9he nucleus mem+rane

reforms3

M i 2


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•

9he nucleus mem+rane isformed again3•our daughter cells are formed3• $ach daughter cell has half ofthe num+er of chromosomes in

the parent cell3

• 'pindle :+res emerge3•Chromosomes align themselves

in the centre of the cell3

• 9he nucleus mem+ranedisappears3

•Chromatids divide and separateto the opposite ends of the cell3

• 9he cell starts to divide3

Meosis 2


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http://youtube.co/watch?v=eaf4j19_3Zghttp://youtube.co/watch?v=eaf4j19_3Zg


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!eiosis

Crossino$er

+ro&ess

Inde+endentassortment

o)&hromosom

es(characteristics are separated

during formation of gameteand randomly combined

during fertilization)

3 9oproducegametes

3 9o allo!

variationthrough

C ' i O) !i i


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Con&'(sion O) !itosisAnd !eiosis

Meiosis

ertilisation

Mitosis

Male

.- chromosomes1

emale

.- chromosomes1

'perm0 chromosomes1

)vum.0 chromosomes

ygote

.- chromosomes1

Ba+y.- chromosomes1

C i ! i i A d !it i


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Com+arin !eiosis And !itosisp//youtu+e3co/!atch4v5BaEL;FH@t&

http://youtube.co/watch?v=Ba9LXKH2ztUhttp://youtube.co/watch?v=Ba9LXKH2ztU


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Simi'arities And Dieren&es2et%een !itosis And !eiosis

SI!ILARITIES

(eplication of DNA

ta#esplace

nvolves

division ofnucleus

andcytoplasm

Celldivisionoccurs

The Dieren&e 2et een !itosis


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The Dieren&e 2et%een !itosisAnd !eiosis

DIFFERENCESMITOSIS MEIOSIS

Replication process

Number of division

Number of daughter

cells produced

Number of

chromosomes indaughter cell

Combination of gene

Occur

One only

Four

Same as in parent cell

Same as parent cell

Occur in the first

division

Two times

Two

Half of parent cell

Different from parent cell

Crossing over processDoes not occur Occur


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.O

INHERITANCEGene

$"ist in pair

Dominant ene

*A gene !hich e"presses

the trait !hen paired !itha dominant or recessive

gene

*Denote as capital letter,eg

T ta''/

Dominant trait

Characteristics controlled

+y dominant genes

Re&essi$e ene

*A gene !hich e"presses thetrait !hen paired !ith a

recessive gene only .in thea+sence of a dominant

gene1

*Denote as small letter, eg t

short/

Re&essi$e trait

Characteristics controlled

+y recessive genes


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Chromosomes are in pair3 )nefrom the father !hile the other

one from the mother3

'ame genesDominant gene andrecessive gene areplaced

opposite to each other

Homologous chromosomes

t T

Eam+'es o) dominant and re&essi$e


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Eam+'es o) dominant and re&essi$etraits

Trait Dominant Re&essi$e

Ear'o*es ree earlo+es Attached earlo+es

To(ne A+ility to roll na+ility to roll

Dim+'es 2resence A+sence

Hair Curly 'traight

Iris&o'o(r

Bro!n Blue

Heiht 9all D!arf


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The !e&hanism O) Trait Inheritan&e

•

Gregory Mendel !as the :rst person!ho discovered the principles ofheredity3

4enoty+e

Phenoty+e

The genetic

information of anorganism

The physicalcharacteristics of an

organism


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!onohy*rid Inheritan&e 2y 4reory !ende'

TT tt

9all .pure +reed1 D!arf .pure +reed1

T T tt

T t tT

9all 9all 9all 9all

9all 9all 9all D!arf

2henotype

Genotype

2henotype Genotype

2henotype

Genotype

Generation

Generation

Gametes

Gametes

Tt Tt Tt Tt

TtTtTT tt

5ey#

Homo6yo(s# *othenes are same

E# TT, ttHetero6yo(s# enesaredierent

E# Tt


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Eer&ise 1

• n the pea plant, the gene for roundseed.(1 is dominant to the gene for!rin#led seed.r13a1 f a homo@ygous round*seeded pea

plant is crossed !ith a homo@ygous!rin#led*seeded plant, !hat !ill +e the

phenotype of plants4+1 f the plants are self*pollinated, !hat!ill +e the genotype and phenotyperatios of the plants4


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RR rr

(ound seed rin#led seed

R R rr

(ound (ound(ound(ound

2arental 2henotype 2arental Genotype

Generation

Gametes

Rr Rr Rr Rr

Hen&e a'' the 1 +'ants ha$e ro(nd seeds.

a1 5ey#R# ro(nd seededr # %rin7'ed

seeded


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+1

R r rR

(ound

(ound

(ound

rin#led

2henotype

Genotype

Generation

Gametes

Rr Rr

RrRrRR rr

notype ratio is 1 RR#0 Rr# 1rr

notype ratio is 3 +'ants %ith ro(nd seeds # 1 +'ant %ith %rin7'ed


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Eer&ise 0

• B represents the dominant gene for+lac# cat, and + represents therecessive gene for a !hite cat3

hat is the phenotype ratio of thenum+er of +lac# cats to the num+erof !hite cats if +lac# fur cat .B+1 is

crossed !ith another +lac# fur cat.B+14

Ans!er


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2 * *2

Blac

#

Blac#Blac# hite

2henotype

Genotype

2arents

Gametes

2* R*

2*2*22 **

henotype ratio is 3 *'a&7 )(r &ats# 1 %hite )(r &at

5ey#R# *'a&7 &atr# %hite &at

Ans!er


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Eersi&e 3

• n the pea plant, the gene for purpleIo!ers .21 is dominant to the genefor !hite Io!ers .p13 A cross

+et!een a hetero6yo(s +ea +'ant%ith +(r+'e 8o%ers and ahomo6yo(s +ea +'ant %ith

%hite 8o%ers is done3hat are the genotypes of theos+rins4

Ans!er


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P + ++

2urpl

e

hite2urpl

e

hite

2henotype

Genotype

2arents

Gametes

P+ ++

++P+P+ ++

Genotype ratio is 0 P+ # 0 ++

5ey#P+# hetero6yo(s ,+(r+'e 8o%er

++# homo6yo(s , %hite8o%er

Ans!er

3 3 SE9 DETER!INATION AND THE


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3.3 SE9 DETER!INATION AND THEOCC:RRENCE O T;INS IN H:!AN 2EIN4S

•

Se &hromosomes the last pair in humanchromosomes

!a'e# pairs of

autosomes and a pair of

ema'e# pairs of

autosomes and a pair of se"


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• Se determination # the se" of +a+y is determined+y the )ather=s s+erm 9>?992a*y *oy>>? 9


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J;;

J; K

J ;

J ;

J;;

J; K

J K

J ;

J;;

J; K

Mother ather

4ametes #

Parents #

s+rins#

Ratio o) da(hter # son is 1#1

There)ore , the &han&e to et da(hter or son is @#@.

Daughter Daughter'on 'on

Th ti O) Id ti ' A d N id ti '


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The ormation O) Identi&a' And NonBidenti&a'T%ins

An ovum is fertilised+y a sperm to form a@ygote3

ygote undergoesmitosis and separates

into t!o to develop intot!o em+ryos3

Genetically identical3

'hare the sameplacenta3

'ame se"3

IDENTICAL

T;INS 9!o dierent ovafertilised +y t!odierent sperms at thesame time3

9!o dierent @ygotesare formed and developinto t!o em+ryos3

Genetically dierent3

$ach has o!nplacenta3

'ame se" or dierent

se"3

NONBIDENTICAL

T;INS


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IDENTICALT;INS


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NONBIDENTICALT;INS


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2:TTT

IDENTICALNONB


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IDENTICALT;INS

IDENTICALT;INS

ygoteundergoes mitosis

9!o

em+ryos

oetusshare thesameplacenta

9!o ovaarefertilise

d

9!odierent@ygotes areformed

9!oseparateem+ryos

$achfoetushas hiso!nplacenta


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• Siamese t%ins – dentical t!ins that are oined at some

parts of the +odies3 – ormed !hen @ygote fails to divide

completely in the course of formation3


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Simi'arities And Dieren&es 2et%een Identi&a' And


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NonBidenti&a' T%insIDENTICAL

T;INS

NONBIDENTICAL

T;INSSimi'arities#

9he t!ins are formed in the uterus3 9!o +a+ies are formed3

)ne

)ne

'ame se"

Kes

'ame / identical

Kes / sharingplacenta

9!o

9!o

'ame or dierentse"

No

Dierent

No / separateplacenta

N(m*er o) s+erms

erti'ised o$(ms+'its into t%o

4eneti& ma7e (+

Sharin o)+'a&enta

Se

N(m*er o) o$a

Dieren&es

y


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ythem4

3 > !:TATION


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3.> !:TATION

• !(tation# the spontaneous changeto the structure of genes orchromosomes

)ccurs in

Somati&-*ody

&e''s.can +e passeddo!n through

mitosis1

4ametes-re+rod(&ti$e &e''s

.inherited1


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T


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Eam+'es O) Chromosome!(tation

• Do%n=s syndrome# an e"tra chromosome

in autosome .< chromosomes1

• 5'ine)e'ter=s syndrome a male !ith

e"tra ; chromosome .;;K1

• T(rner=s syndrome# a female !ith oneless ; chromosome .;)1

• Po'y+'oidy having one or morechromosomes in a set of chromosome

' O) 4 i


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Eam+'es O) 4ene !(tation

• Co'o(r *'indness a mutated gene in the Xchromosome

• Si&7'e &e'' anemia# mutation in gene thatproduces haemoglobin inecient in transportingo"ygen in the +lood

• A'*inism# the gene for sin colour is mutated

una+le to produce +lac# pigment .melanin1

• Haemo+hi'ia# mutation in gene that isimportant for blood!clotting

Eam+'es O) Chromosome


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Eam+'es O) Chromosome!(tation

Do%n=s syndromeAdditiona' chromosome at a(tosome 0

•"hysical retardation•

Thic nec •#lanted eyes•Protuding tounge•Reduced resistance to diseases

5'i ) 't = d


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5'ine)e'ter=s syndrome

A ma'e !ith etra 9

chromosomes .having ;;K1

•$nfertile•%nderde&eloped testes•Narrow shoulder•'nlarged breasts


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T(rner=s syndromeA )ema'e having one 'ess 9chromosome .;)1

•$nfertile•#hort •entally retarded•as no o&aries

•#mall breasts•*olded sin on nec •No menstrual cycle

P ' ' id


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Po'y+'oidy – 9he num+er of chromosomes is

in&reased *y one or more sets.

– More common in plants3


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!(tation

Co'o(r *'indness

!(tant ene .recessive gene1on the 9 chromosome3

•Not able to di+erentiate coloursespecially green and red •ore common in males becausemale has only one Xchromosome


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• Colour Blind


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Colour Blind 9est

A'*inism


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A'*inism

9he ene )or s7in &o'o(r ism(tated .recessive gene1

•%nable to produce melanin(blac pigment)•,hite hair

•"in eyes and pinish sin•#in is sensiti&e to sunlight

Si&7'e &e'' anemia


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Si&7'eB&e'' anemia

!(tation in ene that+rod(&e haemo'o*in

•#icle!cell shaped of red bloodcells•Not e-cient in transporting

oygen•*acing painful crises such aschest pain/

fatigue/ bone pain/•0ellowing of eyes•$nherited from both parents

Haemo+hi'ia


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Haemo+hi'ia

!(tation in &hromosome 9.for +lood clotting1

• a&e problem in blood clotting• ay bleed continuously or fora longer

period• A woman carrier may inheritthe

disease to a son

Ca(ses O) !(tation


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'pontaneouschanges during

cell division

$"posure to

+hysi&a'm(taens &Oradiation, ;*rays,

radioactive radiation

En$ironmenta'&hane# the change oftemperature for a longperiod causes geneticevolution in organism

$"posure to &hemi&a'

m(taens Ben@ene,formaldehyde,nicotine, sodiumnitrite, pesticides

Ca(ses O) !(tation

Ad antaes And Disad antaes


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Ad$antaes And Disad$antaesO) !(tation

*variation di3trait

*more resistantto disease

Advantages

Cause physicaldefects

Causes geneticdiseases

Causes mentaldefects

Disadvantages

.RESEARCH


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RESEARCHON H:!AN LIE

4ene thera+y# to

replace damaged/faultygenes during the foetal

stage4eneti& s&reenin# topredict diseases li#ely

to develop4ene test# to screen

un+orn children fordiseases4eneti& enineerin#

to transfer DNA fromone organism to

anotherH(man enome+roe&t# maps allhuman genes to

determine genes !hichcauses diseases

ie'd o)

!edi&ine


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9o produce plants !hichare resistant to

diseases and infections 9o produce engineeredplants !hich are a*'e

to 'i$e in(n)a$o(ra*'e

conditions

9o produce plants !hichgro! and mat(re )ast

9o produce hiher

yie'ds

9o produce hih(a'ity of crops and

livestoc#

ie'd o)Ari&('t(re

'elective Breeding


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'elective BreedingA process !hich involves

cross breeding and cloning of plants or animals

Ad$antaes

Ne! varieties

9o produce ne!

and high Pualitycrops

More resistant todiseases

Disad$antaes

ne! varieties !ithundesira+le

characteristics

$"ample Co!


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$"ample Co!

is &ross *red %ith

riesian Co% Sahi%a' Co%

!a)ri%a' Co%

*Gro! faster *Bigger in si@e

*More mil# *High resistant to

$"ample 2alm oil


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$"ample 2alm oil

is &ross *red %ith

D(ra Pisi)era

Tenera

*9hic# meso&ar+ and 'are 7enne' #much oil

*Thin she''# easier to e"tract

hineso&ar+

Lare7enne'

Thi&7 meso&ar

Sma''7enne'

Tiss(e C('t(re


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A process of cloning a plant byusing a plant part or single cellin a test tu+e under a controlled

condition

Ad$antaes 9o produce many

copies of thesame plants in ashort time

9o produce plantsanytime !e !ant

'horter

maturation time

No variation

Disad$antaes

Complete !ipe*out of crops if

there is spread ofdiseases

Ste+s o) Tiss(e C('t(re


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Ste+s o) Tiss(e C('t(rea/ E+'ant#

*/ !('ti+'i&ation#

&/ Trans+'antin#

C'onin


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9he process of producing an

organism that is an eactgenetic copy of another

ro&ess#

4eneti&a''y !odi"ed


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yood

*oods from plants and animal!adding genes from anotherorganisms

Ad$antaes#or &ro+s#

enhanced tasteand Puality,

increased yields,matures faster,+etter resistance

to diseases,remain fresh

longer

or 'i$esto&7#increased

resistance toinfections anddiseases, higher

yield of mil#,meat and eggs


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GM2

Disad$antaes o) 4eneti&a''y !odi"ed


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Cause allergies to human+eings

ood and Oranisms#

Mil# of animal may+e unsafe

Anti+iotic*resistant genes inGM organisms may +e pass on

to +acteria dicult to #ill them

Genetic research is e"pensive,poor farmers cannot aord

3.F VARIATION A!ON4 LIVIN4THIN4S


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THIN4SVariation#

9he dierences amongindividuals of the same

species

Contin(o(s $ariation

Dis&ontin(o(s

$ariation

*Characteristics amongindividuals !hich do notsho! distinct dierences

*8uantitative and can +emeasured

*Determined +y genesand can +e inIuenced +yenvironmental factors

*Characteristics amongindividuals !hich sho!distinct dierences

*8ualitative and cannot

+e measured

*Determined +y a singlegene and is notinIuenced +y

environmental factors

Di ti


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Contin(o(s $ariation

Dis&ontin(o(s

$ariation

Height

'#incolour

Lengthof foot

ntelligence

eight

$arlo+es

riscolour

Colour+lindnes

s

9onguerolling

Bloodgroup

a&tors That Ca(se


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Variation

Geneticfactors

Crossin o$er during meiosisgenetic material is e"changed

Random )(sion of male andfemale gametes during

fertilisations

Chromosome and genem(tation creates ne!

phenotypes

Inde+endent assortmentof chromosomes dierent

gametes

$nvironmental factors

S(n'iht e+os(re# !illhave dar#er comple"ion

;ater &'imate,tem+erat(re

+H# the Hydrangea Io!er is+lue in acidic soil and pin# in

al#aline soil

Diet# a person !ho eats alot !ill +e fatter

Im+ortan&e O) Variation


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Im+ortan&e O) Variation

M2)(9ANC$

$nsures the survivalof a species under

changingenvironment

$na+le anyspecies to

occupy a !iderrange of ha+itat

$na+le naturalselection species!ith favoura+le

characteristics !ill+e selected +y

nature

$na+le us todistinguish

individuals ofthe samespecies


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• Discuss the similarities anddierences +et!een continuousvariation and discontinuous variation3

Simi'arities And Dieren&es 2et%eenContin(o(s And Dis&ontin(o(s Variation


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CONTIN:O:SVARIATION

DISCONTIN:O:S VARIATION

Simi'arity#'ho! dierences in characteristics

among individuals of the samespecies

Kes

Not distinct

f it is inIuenced+y environmental

factors cannot +einherited

9!o or moregenes for the

same character8uantitative/ can

+e measured

No

Distinct

Can +e inherited

'ingle gene

8ualitative/cannot +emeasured

In8(en&ed *yen$ironmenta'

)a&torsG

Inheritan&e

No o) ene

Ty+e o) data

Chara&teristi&

Dieren&es

Contin(o(s And Dis&ontin(o(s Variation

3. THE NEED TO ADHERE TO A CODE


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O ETHICS IN 4ENETIC RESEARCH

• Discuss the eects of misusing the#no!ledge of genetics research3

d d f thi QQ


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e need code of ethicsQQ

9he produce of+iological !eapon

anthra" +acteria

GM may have side eectsand endanger human

health,should +e la+elled

Human cloningagainst religion

Manipulation ofhuman genes !hen

carrying out researchon human +eing

Documents

Sains Form 4 Chapter 3