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Samenvatting deeltentamen 1 Genen en Cellen (GZW, jaar 1)
Samenvatting eerste deeltentamen van het vak 'Genen en cellen' (in het Engels)
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Door: demihuisman • 3 jaar geleden
Voorbeeld van de inhoud
Eerste tentamen ‘Genen en cellen’Stof:
Gedeelte cellen:
Biology boek: H1, H2, H3, H4 (4.1, 4.2, 4.4, 4.6, 4.7), H5
Computerpractcum (H2 & H3)
Werkcollege Cystc ibrosis
Gedeelte genen:
Biology boek: H11, H12 (featured investgatonsn ;el: blb. 236 Beadle and Tatum, niet: blb. 245/246 Synthetc RN
helped..), H13 (blb. 264-266 eature Investgatons niet)
Werkcollege Cystc ibrosis
Cellen
Chapter 1: Nn introducton to biology
1.1 Principles of biology and the levels of biological organizaton
The t;elve principles of biology:
Principle 1: Cells are the simplest units of life.
The term organism can be applied to all living things. Organisms maintain an internal order that is separated from
the environment. The simplest unit of such organibaton is the cell. Cell theory: all organisms are composed of cells,
cells are the smallest units of life, and ne; cells come from pre-existng cells via cell division.
Principle 2: Living organisms use energy.
The maintenance of organibaton reeuires energy. Nll organisms aceuire energy from the environment and use that
energy to maintain their internal order. Cells carry out a variety of chemical reactons that are responsible for the
breakdo;n of nutrients. Such reactons ooen release energy in a process called respiraton. Chemical reactons
involved ;ith the breakdo;n and synthesis of cellular molecules are collectvely kno;n as metabolism.
Principle 3: Living organisms interact ;ith their environment.
Nll organisms must respond to environmental changes. or example, the thicker coat of mammals in the ;inter.
Principle 4: Living organisms maintain homeostasis
Nlthough life is a dynamic process, living cells and organisms regulate their cells and bodies to maintain relatvely
stable internal conditons (homeostasis). Nll organisms contnually regulate their cellular metabolism so nutrient
molecules are used at an appropriate rate and ne; cellular components are synthesibed ;hen they are needed.
Principle 5: Living organisms gro; and develop.
Gro;th produces more or larger cells. Development is a series of changes in the state of the cell, tssue, organ or
organisms, eventually resultng in organisms ;ith a defned set of characteristcs.
Principle 6: The genetc material provides a blueprint for reproducton.
To sustain life, organisms must reproduce, or generate ofspring. Nll living organisms contain genetc material
composed of DRN (deoxyribonucleic acid), ;hich provides a blueprint for the organibaton, development and
functon of living things. During reproducton, a copy of this blueprint is transmitted from parent to ofspring. DRN is
heritable. Genes (segments of DRN) govern the characteristcs of organisms. Most genes are transcribed into a type
of RN (ribonucleic acid) molecule called messenger RN that is then translated into a polypeptde ;ith a specifc
amino acid seeuence. N protein is composed of one or more polypeptdes. The structures and functons of proteins
are largely responsible for the traits of living organisms.
Principle 7: Populatons of organisms evolve from one generaton to the next.
Over the long run, another universal characteristc of life is biological evoluton, ;hich refers to heritable change in a
populaton of organisms from generaton to generaton. Ns a result of evoluton, populatons become better adapted
to the environment in ;hich they live.
Principle 8: Nll species (past and present) are related by an evolutonary history.
Evidence sho;s that all organisms on earth share a common ancestry. Biologists ooen vie; evoluton ;ithin the
context of genomes and proteomes. The term genome refers to the complete genetc compositon of an organism or
species. The proteome is the complete protein compositon of a cell or organism.
Principle 9: Structure determines functon.
Principle 10: Re; propertes of life emerge form complex interactons.
When individual components in an organism interact ;ith each other or ;ith the external environment to create
novel structures and functons, the resultng characteristcs are called emergent propertes.
Principle 11: Biology is an experimental science.
Principle 12: Biology afects society.
or example, biologists have discovered drugs that are used to treat many diferent diseases.
,The organibaton of living organisms can be analysed at diferent levels of biological complexity.
1. Ntoms: an atom is the smallest unit of an element that has the chemical propertes of the element.
2. Molecules and macromolecules: atoms bond ;ith each other to form molecules. Many molecules bonded
form a macromolecule. Carbohydrates, proteins and nucleic acids are important macromolecules.
3. Cells: molecules and macromolecules associate ;ith each other to from larger structures and membranes. N
cell is surrounded by a membrane and contains a variety of molecules and macromolecules.
4. Tissues: many cells of the same type associate ;ith each other to form tssues.
5. Organs: an organ is composed of t;o or more types of tssue.
6. Organism: all living things can be called organisms, classifed to a partcular species.
7. Populaton: a group of organisms of the same species that occupy the same environment.
8. Community: a biological community is an assemblage of populatons of diferent species.
9. Ecosystem: these are formed by interactons of a community of organisms ;ith their physical environment.
10. Biosphere: all of the places on the earth ;here living organisms exist.
1.2 Unity and diversity of life
Life began on earth as primitve cells about 3.5-4 billion years ago. Since that tme, populatons of living organisms
under;ent evolutonary changes that ultmately gave rise to the species ;e see today. Understanding the
evolutonary history of species can provide key insights in the structure and functon of an organism’ss body, because
evolutonary change freeuently involved modifcatons of characteristcs in pre-existng populatons. Over long
periods of tme, populatons may change so that structures ;ith a partcular functon become modifed to serve a
ne; functon. Evolutonary change occurs by t;o mechanisms: vertcal descent ;ith mutaton and horibontal gene
transfer. The traditonal ;ay to study evoluton is to examine a progression of changes in a series of ancestors
(lineage). When evoluton occurs in a lineage, it’ss called vertcal evoluton. In this mechanism of evoluton, ne;
species evolve from pre-existng ones by the accumulaton of mutatons (heritable changes in the genetc material of
organisms). N mutaton may alter the traits of organisms in a ;ay that increases their chances of survival and
reproducton. When a mutaton causes such a benefcial change, the freeuency of the mutaton may increase in a
populaton (natural selecton). The most common ;ay for genes to be transferred is in a vertcal manner. Ho;ever,
genes are sometmes transferred bet;een organisms by other mechanisms. These other mechanisms are collectvely
kno;n as horibontal gene transfer, ;hich is the transfer of genetc material from one organism to another organism
that is not ofspring. Genes transferred horibontally may be subjected to natural selecton and promote changes in
an entre species. This has been partcularly important to bacterial species.
The grouping of species (based on their evolutonary history) is termed taxonomy. Nll organisms can be place into
three large categories, called Bacteria, Nrchaea, and Eukarya. Bacteria and archaea are microorganisms that are also
termed prokaryotc, because their cell structure is relatvely simple. Nt the molecular level, bacterial and archaeal
cells sho; signifcant diferences in their compositons. By comparison, organisms in domain Eukarya are eukaryotc
and have larger cells ;ith internal compartments that serve various functons. Eukaryotc cells have a cell nucleus in
;hich the genetc material is surrounded by a membrane. Biologists use a t;o-part descripton, called binomial
nomenclature, to provide each species ;ith a unieue scientfc name. The frst part is the genus, and the second part
is the specifc epithet, or species descriptor.
Genomes and proteomes afect many features of living organisms, including morphology and behaviour.
Multcellular species go through diferent stages of development, beginning ;ith a fertlibed egg and ending ;ith the
adult. The morphology of organisms can change a lot during these stages of development. This is possible, because
diferent genes are expressed at certain stages but not others.
1.3 Biology as a scientic discipline
Biological science is the observaton, identfcaton, experimental investgaton, and theoretcal explanaton of
natural phenomena. Biologists study life at diferent levels, ranging from ecosystems to the molecular components.
Chapter 2: The chemical basis of life I: Ntoms, molecules and ;ater
2.1 Atoms
Nll life-forms are composed of matter, ;hich is defned as anything that contains mass and occupies space. In living
organisms, matter may exist in any of three states: solid, lieuid or gas. Nll matter is composed of atoms, ;hich are
the smallest functonal units of matter that form all chemical substances and ultmately all organisms. Ntoms are
composed of diferent types of smaller, subatomic partcles. Chemists study the propertes of atoms and molecules,
;hich are t;o or more atoms bounded together.
, The chemicals ;ithin living organisms are composed of many diferent types of atoms. Each specifc type of atom is
called an element, ;hich is a pure substance made up of only one kind of atom. Three subatomic partcles protons
(p+), neutrons (n0) and electrons (e-) are found ;ithin atoms. The protons and neutrons are confned to a very small
volume at the centre of an atom, the atomic nucleus, ;hereas the electrons are found in regions at various distances
from the nucleus. In most atoms, the numbers of protons and electrons are identcal, but the number of neutrons
may vary. Each of the subatomic partcles has a diferent electric charge. Protons
have one unit of positve charge, electrons have one unit of negatve charge, and
neutrons are electrically neutral. Like charges repel each other, and opposite charges
attract each other. The positve charges in the nucleus attract the negatvely charged
electrons. Because the protons are located in the atomic nucleus, the nucleus has a
net positve charge eeual to the number of protons it contains. The entre atom has
no net electric charge, because the number of negatvely charged electrons around
the nucleus is eeual tot the number of positvely charged protons in the nucleus.
Chemists vie; electrons existng ;ithin orbitals. Nn orbital is the physical region of space ;here an electron may be
found. Some orbitals are spherical, called s orbitals, ;hereas others assume a shape that is ooen described as similar
to a propeller and are called p orbitals. Nn orbital can contain a maximum of t;o electrons. Conseeuently, any atom
;ith more than t;o electrons must contain additonal orbitals. Orbitals are found ;ithin electron shells, or energy
levels. Energy can be defned as the capacity to do ;ork or cause a change. Electrons have kinetc energy. The
electron shells are numbered, ;ith shell number 1 being closest to the nucleus. Diferent electron shells may contain
one or more orbitals, each orbital ;ith up to t;o electrons. The innermost electron shell of all atoms has room for
only t;o electrons, ;hich spin in opposite directons ;ithin a spherical s orbital (1s). The second electron shell is
composed of one spherical s orbital (2s) and three p orbitals (2p). Therefore, the second shell can hold up to four
pairs of electrons. electrons vary in the amount of energy they have. The shell closest to the nucleus flls up ;ith the
lo;est energy electrons frst, and then each subseeuent shell flls ;ith higher and higher energy electrons, one shell
at a tme. Within a given shell, the energy of electrons can also vary among diferent orbitals. Most atoms have outer
shells that are not completely flled ;ith electrons. Ntoms that have unflled electron shells tend to share, release, or
obtain electrons to fll their outer shell. Those electrons in the outermost shell are called the valence electrons. such
electrons allo; atoms to form chemical bonds ;ith each other.
Each element has a specifc and unieue number of protons in its nucleus. The number of protons is its atomic
number. The number of protons and electrons in a given atom are identcal. Protons and neutrons are nearly eeual
in mass, and each has more than 1800 tmes the mass of an electron. Because of their tny sibe relatve to protons
and neutrons, the mass of the electrons in an atom is ignored in calculaton of atomic mass. The atomic mass scale
indicated an atom’ss mass relatve to the mass of other atoms. Ntomic mass is measured in units called daltons. One
Dalton (Da), also kno;n as an atomic mass unit (amu), eeuals 1/12 the mass of a carbon atom, or about the mass of
a proton or a hydrogen atom. N mole (mol) of any substance contains the same number of partcles as there are
atoms in exactly 12 g of carbon.
Many elements can exist in multple forms, called isotopes, that difer in the number of neutrons they contain.
Isotopes of an atom have similar chemical propertes but may have very diferent physical propertes. or example,
many isotopes found in nature are inherently unstablen the length of tme they persist is measured in half-lives the
tme it takes for 50 of the isotope to decay. Such unstable isotopes are called radioisotopes. They emit radiaton,
;hich converts them to a stable form. Modern medical treatment and diagnosis make us e of the special propertes
of radioactve compounds in many ;ays. or example by using fuorodeoxy-glucose to detect ;hether organs are
functoning normal (by their glucose intake) by using a PET-scan.
Just four elements (oxygen, carbon, hydrogen, and nitrogen) account for the vast majority of atoms in living
organisms. Much of the oxygen and hydrogen occur in the form of ;ater. Carbon is a major building block of all living
matter, and nitrogen is a vital element in all proteins. Other important elements in living organisms include the
mineral elements. In additon, all living organisms reeuire trace elements. These elements are present in extremely
small euanttes but stll are essental for normal gro;th and functon (iron for example).
2.2 Chemical bonds and molecules
T;o or more atoms bonded together make up a molecule. T;o oxygen atoms can combine to one, as O 2. This is
called a molecular formula. It consists of the chemical symbols for all of the atoms that are present and a subscript
that tells you ho; many of those atoms are present in the molecule. The term compound refers to a molecule
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