Figure 17.0 Ribosome. DNA and protein DNA codes for your traits So you are different from other...

Figure 17.0 Ribosome

DNA and protein

• DNA codes for your traits

• So you are different from other people because your DNA is different

• DNA works by creating proteins

• So you are different from other people because your DNA makes different proteins

Protein Structure

• A protein is made up of hundreds or thousands of amino acids put together

• There are 20 different amino acids

• One protein is different from another because of the order of the amino acids

Amino Acids

O

O–

H

H3N+ C C

O

O–

H

CH3

H3N+ C

H

C

O

O–

CH3 CH3

CH3

C C

O

O–

H

H3N+

CH

CH

3

CH

2

C

H

H3N+

CH

3

CH

3

CH

2

CH

C

H

H3N+

C

CH

3

CH

2

CH

2

CH3N+

H

C

O

O–

CH

2

CH3N+

H

C

O

O–

CH2

NH

H

C

O

O–

H3N+ C

CH2

H2

C

H2

NC

CH

2

H

C

Nonpolar

Glycine (Gly) Alanine (Ala) Valine (Val) Leucine (Leu) Isoleucine (Ile)

Methionine (Met) Phenylalanine (Phe)

C

O

O–

Tryptophan (Trp) Proline (Pro)

H3C

Figure 5.17

S

O

O–

O–

OH

CH2

C C

H

H3N+

O

O–

H3N+

OH CH3

CH

C C

HO–

O

SH

CH2

C

H

H3N+ C

O

O–

H3N+ C C

CH2

OH

H H H

H3N+

NH2

CH2

O

C

C C

O

O–

NH2 O

C

CH2

CH2

C CH3N+

O

O–

O

Polar

Electricallycharged

–O O

C

CH2

C CH3N+

H

O

O–

O– O

C

CH2

C CH3N+

H

O

O–

CH2

CH2

CH2

CH2

NH3+

CH2

C CH3N+

H

O

O–

NH2

C NH2+

CH2

CH2

CH2

C CH3N+

H

O

O–

CH2

NH+

NH

CH2

C CH3N+

H

O

O–

Serine (Ser) Threonine (Thr)Cysteine

(Cys)Tyrosine

(Tyr)Asparagine

(Asn)Glutamine

(Gln)

Acidic Basic

Aspartic acid (Asp)

Glutamic acid (Glu)

Lysine (Lys) Arginine (Arg) Histidine (His)

Protein shape

• Placing amino acids in a certain sequence will cause a protein to have a different shape

• The shape of the protein affects its function

Shape and function

• If you change the shape of a protein it will not work in the same way

• You can change the shape of a protein by changing the order of the amino acids

• An example of this is with sickle cell anemia

Changing a protein’s shape affects its function

Normal hemoglobin

Sickle-cell hemoglobin

Overview of protein synthesis

1

2

3

Synthesis of mRNA in the nucleus

Movement of mRNA into cytoplasm

via nuclear pore

Synthesisof protein

NUCLEUS

CYTOPLASM

DNA

mRNA

Ribosome

AminoacidsPolypeptide

mRNA

Figure 5.25

Figure 17.3 The triplet code

Figure 17.4 The dictionary of the genetic code

Paired Activity

• Create a polypeptide that is 8 amino acids long

• Choose any amino acids that you want, but must have a start and stop codon

• Begin by listing the 8 amino acids that you want

• Use arrow to show which bases you will need for mRNA

• Use arrows to show bases for DNA

Figure 17.5 A tobacco plant expressing a firefly gene

Elongation

RNApolymerase

Non-templatestrand of DNA

RNA nucleotides

3 end

C A E G C AA

U

T A G G T TA

AC

G

U

AT

CA

T C C A AT

T

GG

3

5

5

Newly madeRNA

Direction of transcription(“downstream) Template

strand of DNA

Figure 17.6 The stages of transcription: initiation, elongation, and termination (Layer 1)

Figure 17.6 The stages of transcription: elongation

Figure 17.12 Translation: the basic concept

The structure of tRNA

Amino Acids attach here

Matches with codon on mRNA

Figure 17.17 The initiation of translation

Figure 17.18 The elongation cycle of translation

Figure 17.19 The termination of translation

Figure 17.25 A summary of transcription and translation in a eukaryotic cell

Mutations

• Are changes in the DNA

• Can only be passed on to offspring if they occur in a sex cell

• Point mutation is a where only one or a few bases are affected

Figure 17.23 The molecular basis of sickle-cell disease: a point mutation

Normal

Figure 17.24 Categories and consequences of point mutations: Base-pair substitution

Figure 17.24 Categories and consequences of point mutations: Base-pair insertion or deletion

Mutations

• Are spontaneous and random

• Naturally happen

• Increase in mutations by things like radiation, smoking, etc…

Figure 17.6 The stages of transcription: elongation

Figure 17.8 RNA processing; addition of the 5 cap and poly(A) tail

Figure 17.9 RNA processing: RNA splicing

Figure 17.12 Translation: the basic concept

Figure 17.13b The structure of transfer RNA (tRNA)

Figure 17.15 The anatomy of a functioning ribosome