Molecules of Life & Cell Structures and Functions

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NURUL AQILAH BINTI AZMEL
H8T03A

MS2213104967
MADAM PUTERI BALQIS BINTI

MOHD ISHLI



SET A

Main Types of Molecule of
Life

PROTEIN WATER

CARBOHYDRATES

DNA & RNA LIPIDS

Structure of Water Molecule
STRUCTURE
H O
Water molecules consist of an oxygen atom and two hydrogen atoms. In water
HYDROGEN molecules, two hydrogen atoms form polar covalent bonds (sharing of
BOND electrons) with an oxygen atom. Water is a polar molecule because its electrical
charge is distributed unevenly, which also means that the molecule's charges
BETWEEN are in opposition to one another. With the three atoms forming a wide V shape
WATER rather than a straight line, the two hydrogen atoms are at an angle of 104.5°.

MOLECULES H EXPLANATION
(BY
Hydrogen bonds are created between water molecules as a result of the
COHESIVE attraction of opposing partial charges. This is so because the hydrogen atom
FORCE) is drawn to the oxygen atom, which is another strongly electronegative
atom. A partial positive hydrogen of one H20 molecule is attracted to the
H partial negative oxygen of nearby H20 molecule. Hydrogen bonds can be

O formed between a water molecule and a maximum of 4 other water
H molecules, and these connections can change over time due to hydrogen

bonds thatconstantly being formed and broken as the water molecules slide
past each other. Despite being weaker than covalent connections, hydrogen
Θ 104.5° bonds are powerful enough to hold H20 molecules together.

Structure of Water Molecules
in:

SPACE-FILLING MODEL ELECTRON MODEL

Oxygen attracts the shared
electrons and is partially negative.

Hydrogens are partially positive

Properties of Water

During hot days or after we do physical activities, our body temperature will increase. This
is due to the fact that heat is produced as your muscles work, and only about 20% of the
energy produced during muscular contraction is used for muscle contraction while the
remaining 80% is converted to heat energy, which raises muscle temperature.
The heat is distributed to the body by the circulation and thus increases body
temperatures. Our hypothalamus, a little area of the brain,signals to the


eccrine sweat glands that are dispersed throughout our body that it is time

to start cooling down by creating sweat as soon as our body's internal
temperature starts to rise. Water has high latent heat of vaporisation. Latent
heat of vaporisation is the amount of energy that must be added to a liquid
substance, to transform a given quantity of the substance into a gas. Water

needs or absorbed heat energy amounted 580 calories to break the hydrogen bonds in order
to turn 1 g of water from liquid state into water vapor. This is because hydrogen bonds will
be broken down so that water molecules can be separated.

When sweating , the separation of water molecules allows the water to evaporate from the
skin which results in loss of body heat. Specifically, when evaporation occurs, the heat is
taken from the water that remains in the liquid state, resulting in a cooler liquid. Hence, it
removes excess heat from the body.

Adaptations of Elephants in Cooling Down

Through ears heat escapes to
the surrounding
As blood supplies heat to all parts of the body, it helps the elephants


to maintain the body temperature. However the heat in the blood can

increase due to hot weather or metabolic activities. Elephants use
their ears to assist in cooling since they do not sweat. The big
elephant's ears are full of blood veins that are near to the skin and
act as heat radiators, transferring body heat to the environment. The
elephant's ears allow blood heat to escape into the atmosphere,
which cools the blood as it flows through a network of capillaries
there and, in turn, cools the body of the elephant.

Through skin

Elephants control much of their body temperature through evaporative cooling through
the skin by bathing or spraying. The skin of the elephants that is getting thicker and
thicker over the dermis causing cracks between the papillae. The water subsequently
enters the crevices from the papillae's cracks via capillary action. The skin surface
becomes an extensive network of channels or called as crevices as a result of this
process. A elephant's skin has folds and folds that catch and hold moisture. Elephant


skin can therefore hold up to 10 times more water than human skin.

capillary action

skin layers causing
cracks
between crevices
papillae

Osmosis

Both passive and active transport are used to move material across the plasma membrane.
Osmosis, which is one of the passive transport, is a movement of water molecules from higher
water potential region to lower water potential region across a selectively permeable
membrane until equilibrium is reached. The selectively permeable membrane is resistant to
some solutes like molecules of sucrose but selectively permeable to water. Osmotic solutions
come in three varieties which are isotonic solution, hypertonic solution, and hypotonic
solution. When there is a difference in the potential of the solutions in the two locations that
are in touch, for hypertonic solution, water will diffuse in and for hypotonic solution,water will
diffuse out until the potential is constant across the
osmotic pressure. One of the examples, the absorption
of water from the soil is due to osmosis. The plant roots
have a higher concentration than the soil. Therefore, the
water flows into the roots. While in the isotonic solution,
water potential in the solution is the same as in the cell.

semipermeable membrane

Types of Passive Transport

Osmosis Facilitated Diffusion Simple Diffusion

They are all passive transport.
Does not require energy to move across plasma membrane.

Occurs following the concentration of the gradient.

Osmosis occurs only in a liquid medium. Diffusion can occur in any medium, whether it is liquid, solid, or gas.
Diffusion does not require a selectively permeable membrane.

Osmosis requires a selectively permeable Any type of substance moves from an area of highest energy or concentration to
a region of lowest energy or concentration.
membrane as it could be impermeable to
some solutes such as sucrose. Involves lipid-insoluble molecules Involves lipid-soluble molecules
Only water or another solvent moves from such as ions, large molecules such such as (fatty acids and glycerol),
a region of high energy or water potential as amino acids and glucose. oxygen and carbon dioxide.
to a region of lower energy or water Substances move across the Substances may move across the
potential. membrane with the aid of transport membrane without the presence of
protein (channel protein and carrier plasma membrane.
protein).

Thank You!