bms129 lecture 5

7/21/2019 BMS129 Lecture 5

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BMS129

Lecture 5

1. Describe the structure of DNA and explain how it is organised in

the nucleus• DNA is wound into thin threads (chromatin) long thin threads with rotein

• Non!di"iding state # DNA molecules comacted

o coiled around core article (histone rotein)

o $ig$agged% looed and coiled onto itself

• &rearing to di"ide

o DNA coies itself to form 2 arallel sister chromatids of a

chromosome

• DNA # ol'mer of nucleotides

7/21/2019 BMS129 Lecture 5


• ach nucleotide consists of

1 hoshate grou

2 sugar

• ri*ose (+NA)

• deo,'ri*ose (DNA)

(-S a sugar

molecule)

. nitrogenous *ase

• in this icture #

adenine

Nitrogenous Bases

• &urines ! dou*le ring

• guanine

• adenine

• &'rimidines ! single ring

• uracil ! +NA onl'

• th'mine ! DNA onl'

• c'tosine / *oth

• DNA *ases #0A

• +NA *ases # 03A

0omlementar' Base &airing

• Nitrogenous *ases united *' h'drogen

*onds

• DNA *ase airings

• A! and 0!

• Law of comlementar' *ase airing

• one strand determines *ase

se4uence of other

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The secquence code for a protein.

2. Compare the structure and function of DNA "s +NADNA

• DNA codes for rotein s'nthesis

• ene ! se4uence of DNA nucleotides that codes for one rotein(mostl'

en$'mes)

• enome ! all the genes of one erson (all the genes for one erson

stimated at .!.5 genes)

• humans ha"e estimated .!.5% genes

• other 967 of DNA non!coding / 8un:; or regulator'

+NA< Structure and =unction N- >?M@N 3+@S@L

• +NA smaller than DNA (fewer *ases)

• transfer +NA (t+NA) ! 9 *ases (smallest)

• messenger +NA (m+NA) o"er 1% *ases (Short)

• +i*osomal +NA (r+NA) (+i*osomes)

• DNA has o"er a *illion *ase airs

•-nl' one nucleotide chain (not a dou*le heli,)

• ri*ose relaces deo,'ri*ose as the sugar

• uracil relaces th'mine as a nitrogenous *ase

• ssential function

• interret DNA code (interreting DNA code into rotein)

• DNA is onl' found within the nucleus +NA in c'tolasm

•+NA is single stranded

•

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•

direct rotein s'nthesis in the c'tolasm not the nucleus (DNA)

3. Dene the genetic code and describe how DNA codes for rotein

structureN@0 0-D

• Bod' can ma:e millions of diCerent roteins% all from the same 2 amino

acids% and encoded *' genes made of ust four nucleotides (A% % 0%

)*ased on . nucelotides will ma:e u the *ase for a neclaic acid

• enetic codea s'stem that ena*les these four nucleotides to code for

the amino acid se4uence of all roteins

• Minimum code to s'm*oli$e 2 amino acids is three nucleotides er amino

acid

enetic 0ode

S'stem that ena*les the E nucleotides (A%%%0) to code for the 2 amino acids

• Base trilet<

• found on DNA molecule

• nucleotides that stand for 1 amino acid

•

0odon<

7/21/2019 BMS129 Lecture 5


• 8mirror!image; se4uence of nucleotides found in m+NA

• FE ossi*le codons (E.) that code for 2 amino acids

• often 2!. codons reresent the same amino acid

• start codon = AUG (also codes for methionine)

• stop codons = UAG! UGA! UAA

4. &rotein s'nthesisG explain the rocess of transcrition&re"iew of &rotein S'nthesis

• ranscrition

• messenger +NA (m+NA) is formed ne,t to an acti"ated gene

• m+NA migrates to c'tolasm

• ranslation

• m+NA code is 8read; *' ri*osomal +NA as amino acids are

assem*led into a rotein molecule DNA in nucleus canHt get to

+i*osome Ie made a co'

transfer +NA deli"ers the amino acids to the ri*osome

ranscrition

• 0o'ing instructions from DNA to +NA

• +NA ol'merase *inds to DNA

• at site selected *' chemical messengers from c'tolasm

• oens DNA heli, and transcri*es *ases from 1 strand of DNA into

re!m+NA

• if 0 on DNA% is added to m+NA

• if A on DNA% 3 is added to m+NA% etc

• rewinds DNA heli,

5. &rotein s'nthesisG explain the rocess of translationStes in ranslation of m+NA

• 0on"erts alha*et of nucleotides into a se4uence of amino acids to createa seciJc rotein

7/21/2019 BMS129 Lecture 5


• +i*osome in c'tosol or on rough +

• small su*unit attaches to m+NA leader se4uence

• large su*unit oins and ulls m+NA along as it 8reads; it

• start codon (A3) where rotein s'nthesis *egins

• small su*unit *inds acti"ated t+NA with corresonding anticodon

• large su*unit en$'me forms etide *ond

•

"teps in Translation of m#$A

• rowth of ol'etide chain

• ne,t codon read% ne,t t+NA attached% amino acids oined% Jrst t+NA

released% rocess reeats and reeats

• Sto codon reached and rocess halted

• ol'etide released and ri*osome dissociates into 2 su*units

7/21/2019 BMS129 Lecture 5


•

• Acti"ation *' A& *inds seciJc amino acid and ro"ides necessar' energ'

to oin amino acid to growing rotein molecule

• Anticodon *inds to comlementar' codon of m+NA

6.Describe how DNA is relicated

7/21/2019 BMS129 Lecture 5


• Law of comlementar' *ase airing allows *uilding of one DNA strand

*ased on the *ases in 2nd strand

• Semiconser"ati"e relication

o each new DNA molecule contains one new heli, and one conser"edfrom arent DNA

• Stes of relication rocess

o DNA helicase oens short segment of heli,

relication for: is oint of searation of 2 strands

o DNA ol'merase assem*les new strand of DNA ne,t to one of the

old strands

1 2 DNA ol'merase en$'mes at wor: simultaneousl'

7/21/2019 BMS129 Lecture 5


7. %ist and describe the E main hases of the cell c'cle0ell 0'cle

• 1 hase% the Jrst ga hase

• accumulates materials needed

to relicate DNA

• S hase% s'nthesis hase

• DNA relication

• 2 hase% second ga hase

• relicates centrioles

• s'nthesi$es en$'mes for di"ision

• M hase% mitotic hase

• nuclear and c'tolasmic di"ision

• hase% cells that ha"e left the c'cle

• 0ell c'cle duration "aries *etween cell t'es

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• g1 e"er'thing

gets read'

• 2 di"ides

•

8. %ist the hases of mitosis and summarise the e"ents that occur ineach hase

Mitosis

• one cell di"ides into 2 daughter cells with identical coies of DNA

• =unctions of mitosis

• em*r'onic de"eloment

• tissue growth

• relacement of dead cells

• reair of inured tissues

• &hases of mitosis (nuclear di"ision)

• rohase% metahase% anahase% telohase

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Mitosis< &rohase 1

• 0hromatin coils into geneticall' identical% aired% sister chromatids

• each chromatid contains a DNA molecule

• remem*er< genetic material (DNA) was dou*led during S hase of

interhase

• hus% there are EF chromosomes with 2 chromatidsKchromosome and 1

molecule DNA er chromatid

7/21/2019 BMS129 Lecture 5


Mitosis< &rohase 2

• Nuclear en"eloe disintegrates

• 0entrioles srout microtu*ules that ush them aart and towards each

ole of the cell

• sindle J*ers grow towards chromosomes

• attach to :inetochore on side of centromere

•

sindle J*ers ull chromosomes towards cell e4uator

Mitosis< Metahase

• 0hromosomes line u on one e4uator

• Mitosis sindles Jnished

• sindle J*ers (microtu*ules) attach centrioles to long centromere

• shorter microtu*ules anchor centrioles to lasma mem*rane (aster)

Mitosis< Anahase

• n$'me slits 2 chromatids aart at centromere

• Daughter chromosomes mo"e towards oosite oles of cells with

centromere leading the wa'

• motor roteins in :inetochore mo"e centromeres along sindle

J*ers as J*ers are disassem*led

• Mitosis< elohaseNew nuclear en"eloes formed *' rough +

• 0hromatids uncoil into chromatin

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• Mitotic sindle *rea:s down

• Nucleus forms nucleoli

0'to:inesis

• Di"ision of c'tolasm into 2 cells

• o"erlas telohase

• M'osin ulls on microJlaments of actin in the mem*rane s:eleton

• creates crease around cell e4uator called clea"age furrow

• 0ell inches in two

• interhase has *egun

7/21/2019 BMS129 Lecture 5


bms129 lecture 5

Documents

protein dna

dna nucleotides

dna bases

dna code interpreting

thymine dna

function of dna

structure of dna

dna molecules