Brown Minimal Modern Woman Photo Book Cover

BIOLOGY 1 (SB015) ASSIGNMENT
2022/2023-

BIO FLIPBOOK: MOLECULES OF LIFE &
CELL STRUCTURES AND FUNCTIONS

SET C

NAME : TEH NURZULAIKHA BINTI
ZABIDIN

PRACTICUM :H8T02B
MATRIC NO :MS2218115001




ORIGINAL
EDITION

Content

1.Main Types of Molecules
2. Main Types of Lipid
3. Structure of Plasma Membrane
4. How certain type of lipids ensure
the fluidity of plasma membrane
while some other type of lipid may
reduce its fluidity?

Main Types of
Molecule

Water

Carbohydrates

Lipids


Proteins

DNA and RNA molecules

Main Type of

Lipids

Triglycerides

also known as triacylglycerol (fats and oils)
made up of one molecule of glycerol and three molecules of
fatty acids that joined by ester bonds via condensation
reaction
Glycerol also known as propane-1,2,3-triol
fatty acid has a long chain of hydrocarbon. The long
hydrocarbon makes it hydrophobic. It can be divided into
1. saturated - solid at room temperature

- no double bond between carbon atom in a chain
2.unsaturated- liquid at room temperature

- 1 or more double bonds between carbons

It could store twice energy as the same mass of carbohydrate.
Do not dissolve in water, so do not cause problems with osmosis
in cells

Stereoids

contain four rings of hydrocarbons with various side
chains
Many animal hormones are steroids including oestrogen
and testerone
a type of cholestrol which is component in cell membrane
structure of stereoids which vary in the functional groups
attached to the four interconnected carbon rings:

Major function of steroid

Cholesterol - Major component Bile acids - When in the form of bile
of the cell membrane, precursor salts, they help in emulsifying fats and
of the other stereoids digestion of fats

Adrenocortical - Hormones Oestrogen and progesterone -
manufactured in the cortex region Female reproductive hormones
of the adrenal gland, involved in
stress Ecdysone - Hormone that causes
ecdysis or moulting in insects
Testosterone - Male
reproductive hormone

Phospholipids

The major part of the cell membrane
The phospholipid molecule is formed during a condensation
reaction between one molecule of glycerol with two molecules of
fatty acids and one molecule of fatty acids
can be divided into two parts:

1. hydrophilic head - contains a phosphoric acid and a
glycerol

2. hydrophobic tail - contains two molecules of fatty acids

example; lecithin
- phospholipids bond to choline to form lecithin molecules
- important component of the cell membrane

Structure of Plasma
Membrane

Structure Fluid Mosaic Model

Describe by the Fluid Membrane is composed off 2
Mosaic Model layers (bilayer) of
phospholipids with globular
Amphipathic molecules have proteins embedded in the
-hydrophobic region : non-polar / bilayer
water hating Fluid: phospholipids &
-hydrophilic: polar / water loving proteins can move laterally
(move side to side)
Mosaic: proteins are
embedded in the phospholipid
bilayer like the mosaic tiles
embedded in mortar
Accounted for the amphipathic
characteristic of phospholipids
& proteins

Phospholipids

The hydrophilic heads of phospholipids facing outwards and attracted to
the surrounding
The hydrophilic tails of phospholipids facing inwards
Molecules that can pass through : water, urea, gases: oxygen, carbon
dioxide and lipid soluble substance
Molecules that cannot pass through: ions, polar and large molecules
(eg: glucose)

Proteins

Intrinsic / Integral proteins: partially embedded or fully
embedded (transmembrane protein)
Extrinsic / Peripheral proteins: attached to the outer & inner
surfaces of the membrane

Carbohydrate chain / oligosaccarides
Found on the the external surface of the plasma membrane

- Carbohydrate chain attaches to protein into glycoprotein
- Carbohydrate chain attaches to phospholipids into glycolipid
- Function as cell identity markers / recognition

Cholesterol

Found between phospholipids
Function: Increase flexibility and stabilizes the
membrane structureby regulating the fluidity of the
membrane

How certain type of lipids ensure the fluidity of
plasma membrane while some other type of lipid may

reduce its fluidity?

At low temperatures:

- The presence of embedded cholesterol will prevent the
hydrophobic tails from closely arrange when
membrane tends to solidify at low temperature

- The plasma membrane remains fluid

At moderate temperature

- Plasma membrane tends to be fluid when temperature
increases.

- Cholesterol embedded in membrane will reduce the
movement of the phospholipid molecules due to van
der Waal interactions

- The fluidity of plasma membrane is reducing