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Summary Introduction to biology (VSC1101)
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Overview, summary for the mid-term exam introduction to biology. For students of UCV and pre-master students HFIM
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INTRODUCTION TO BIOLOGYVSC1101
TABLE OF CONTENTS
Lecture 1 Introduction to Biology ................................................................. 2
Tutorial 1: how important is water and chemistry of life .................................. 6
Tutorial 2: The cell, the basic unit of life ...................................................... 10
Lecture 2: The working cell ....................................................................... 14
Tutorial 3: Why do energy and metabolism matter to me? ............................. 23
Tutorial 4: the nucleus and its information ................................................... 27
Lecture 3: Genetic, DNA and cell division .................................................... 31
Lecture 4: Gene expression and control ...................................................... 34
Tutorial 5: Cell division ............................................................................. 42
,Lecture 1 Introduction to Biology
Biology is the scientific study of life
Properties include:
1. Order, the highly ordered structure typifies life
2. Reproduction, the ability of organisms to reproduce their own kind
3. Growth and development, consistent growth and development controlled
by inherited DNA
4. Energy processing, the use of chemical energy to power an organism’s
activities and chemical reactions
5. Regulation, an ability to control an organism's internal environment within
limits that sustain life
6. Response to the environment, an ability to respond to environmental
stimuli
7. Evolutionary adaptation — adaptations evolve over many generations, as
individuals with traits best suited to their environments have greater
reproductive success and pass their traits to offspring.
Life’s chemistry is tied to water:
- Life first evolved in water.
- All living organisms require water.
- Cells consist of about 75% water.
Organisms are composed of elements, in combinations called compounds. An
element is a substance that cannot be broken down to other substances by
ordinary chemical means, there are 92 elements.
- Macroelements: O, C, H, N (96,3%)
- Microelements: Ca, P, K, S, Na, Cl, Mg (3,7%)
A compound is a substance consisting of two or more different elements in a
fixed ratio. They are more common than pure elements. Elements consist of one
kind of atom; an atom is the smallest unit of matter that still retains the
properties of an element. In an atom: protons, electrons and neutrons.
Isotopes: different isotopes of an element have the same number of protons,
but different numbers of neutrons.
,Chemical bounds
Only electrons are directly involved in the chemical activity of an atom. Electrons
can be located on different electron shells.
- First shell/ orbital: lower energy level-> 2 electrons
- Second shell/orbital: higher energy level->up to 8 electrons
The number of electrons in the outermost shell, called the valence shell,
determines the chemical properties of the atom. Atoms whose outer shells are
not full tend to interact with other atoms in ways that enable them to complete
or fill their valence shells.
- Chemical bond: attractive force that arises between two atoms when
their electrons interact.
- Molecule: group of two or more atoms joined by chemical bonds.
- Compound: molecule that has atoms of more than one element.
Chemical bound: Covalent, Ionic and Hydrogen
Covalent bond:
- Two atoms with one unpaired electron share a pair of electrons.
- Atoms connected by covalent bonds make a molecule.
- The atoms compete for shared electrons, the attraction (pull) is
electronegativity.
➔ Polar: electrons shared unequally
➔ Nonpolar: electrons shared equally
Ionic bond: attractions between ions of opposite charge
In living organisms, most strong chemical bonds are covalent, connecting atoms
to create the molecules in cells.
- For a cell to function properly, weaker bonds within and between molecules
are also important.
- One key type of weak bond is the hydrogen bond, which is best shown
with water molecules.
, Hydrogen bonds: the hydrogen atoms in a water molecule are connected to
oxygen by polar covalent bonds.
- Because of these polar bonds and the V shape of
the molecule, water is a polar molecule with an
uneven charge distribution.
- This partial positive charge on hydrogen attracts it
to nearby atoms with partial negative charges.
- Hydrogen bond between water molecules give
water unique properties that make life possible;
capacitiy to dissolve many substances/cohesion/temperature stability.
Water molecules bond their hydrogen together polar (hydrophilic) substances
and repel nonpolar (hydrophobic) substances.
o Hydrophilic (water-loving) –a substance that dissolves easily in water
o Hydrophobic (water-dreading) - a substance that resists dissolving in
water.
Molecule A dissolves better in water, because it
consists of more O molecules that can form
hydrogen bonds.
Water molecules have cohesion, which helps sustain multicellular
bodies and resists evaporation.
o Cohesion: tendency of molecules to stick together
o Evaporation: process in which the molecules escape from
the surface of a liquid and become vapor. Absorbs heat energy (cooling effect)
and thus lower’s the liquid’s temperature.
Acids and Bases:
pH: concentration H+
Neutral: pH 7
Acids: release H+ ions, pH <7
Base: release OH- ions, pH >7
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