Flipbook SB015

K1T01A

CHAPTER 2 :
MOLECULES OF

LIFE

MAISARAH AL-HUSNA BINTI SULAMI
MS2213201529

PUAN HABIBAH BINTI MOHAMAD
REJAB

SET D
Questions

Table of Contents

01 The main types of molecules of life
02 The main classes of protein

Table of Contents

03 Structure of hair protein

04 The types of muscle tissue

01

The Main Types of
Molecule of life

There are 5 types

Carbohydrates Lipids

Water

Nucleic acids

Proteins

02

The Main Classes
of Proteins

There are three classifications

Classification of Proteins

Based on structure

Fibrous Globular Conjugated

Fibrous

● Mostly secondary structure
● Contain polypeptide chains
● Form long parallel filaments or

strands
● Insoluble & stable
● Function : mechanical & structural

support
● Eg: Keratin, actin, myosin, collagen,

silk

Globular Protein

● Mostly tertiary/quaternary structure
● Folded to form compact spherical

shaped
● Relatively unstable
● Relatively soluble ~ colloid
● Function : metabolic & chemical

process

Conjugated Proteins

● Protein that can function well if it joins with other compound
● Non-protein compound ~ prosthetic group

Conjugated Protein Prosthetic Group Location

Glycoprotein Polysaccharide Component of cell membrane
Mucin (in saliva)

Lipoprotein Lipid Component of cell membrane
Lipid transported in blood
Chromoprotein Pigment plasma
Nucleoprotein Nucleic acid
Myoglobin, hemoglobin

Chromosome, ribosome

03 HOTS Question

A girl with curly hair would like
to make her hair straight. How

this can be done in relation
with the structure of the hair

protein?

-Hair straightening as a cosmetic process is the reverse of hair
waving. It removes hair curliness and makes wavy hair become
straight.
-Keratin, which is fibrous protein consisting polypeptide chain
organised as long strand.
-It also shrug secondary level of protein structure and it coiled due
to hydrogen bond.
-The hair straightening can be done in relation with the structure of
the hair protein by using heat through the denaturation process.
-Curly hair is made straight through hair exposing using high

temperature.

-Proteins are easily damaged by heat (temperature greater than 40 °

C) due to the breakage of their cross linkages.

-This will cause the protein molecules to open up, straighten the fold

and assume a random configuration.

-Protein folding is a very sensitive process that is influenced by several external
factors including electric and magnetic fields, temperature, pH, chemicals,
space limitation and molecular crowding.
-These factors influence the ability of proteins to fold into their correct
functional forms.
-High temperature cause denaturation on the keratin bond.
-Keratin loses it original conformation.
-Apart from heat, chemicals that bring about extreme pH, mechanical forces and
chemical denaturants can also denature proteins.

-During denaturation, proteins lose their secondary structures and become a

random coil.
-Although denaturation is not always reversible, some proteins can re-fold under
certain conditions.

-The prime requirement for an effective hair straightening treatment is to be

able to induce supercontraction of the hair fiber.

04

The Types of
Muscle Tissues

There are 3 types

Each type of muscle tissue in
the human body has a unique
structure and a specific role.

SKELETAL MUSCLE

STRUCTURE

-have cylindrical shape, very long muscles called
fibres
-unbranched
-contain many protein fibers; myofibrils
has many nucleus (multinucleated) located below
plasma membrane .
-Sarcoplasm = the cytoplasm, contains many
mitochondria
-striated muscle with myofibrils
-each cell divided into a functional unit known as
sarcomereconsist of filaments; actin & myosin
-the arrangement of filaments gives light & dark
bands

SMOOTH MUSCLE

STRUCTURE

-single cell, a central nucleus
-have spindle shape
-unbranched
-elongated spindle-shape, pointed ends
-unstriated (no cross-striations)

CARDIAC MUSCLE

STRUCTURE

-Striated
-Branched
-Have one or two centrally located
nucleus
-Have elongated, cylindrical
branched fibers that interconnect via
intercalated disc - relay signals form
cell to cell
-Located in the walls of the heart

THANK YOU!