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Summary Peason IB Biology HL CHapter Summaries
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Summary of 34 pages for the course IB Biology at Arı Anatolian High School (chapter summaries)
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CHAPTERSUMMARIES
,Chapte
C er 1: Cells
1 The cell theeory states that
t living organisms are composed of
o cells, that cells are thee smallest unit of life, and
d
that cells ccome from pre-existing ceells.
2 Scale bars or stated maagnificationss enable you to determine the actual size of specimens.
3 It is essential that a higgh surface area to volume e ratio existss for a cell. As
A a cell increeases in size, the volume
increases mmuch faster thant the surfface area, th
hus decreasin ng the surfacce area to vo olume ratio. This
T decreasses
the chancees of the succcessful existeence of the cell.
c
4 Cells show emergent properties. Th his means th
hat the interaaction of the parts of the
e cell results in the wholee
being greatter than the sum of its parts.
5 In multicellular organissms, cells diffferentiate to
o carry out sp
pecialized functions. Thiss specialization occurs ass a
result of diifferential exxpression of genes
g in a multicellular
m o
organism.
6 Stem cells have yet to go
g through the
t differentiation process. Thus theyy maintain th he ability to differentiatee
along different pathwaays. There ap
ppear to be stem
s cells in most major types of tissues.
7 Stem cells have many therapeutic
t u
uses, including the replaccement of daamaged bon ne marrow ceells in
leukaemia patients. In the future, itt may be posssible to treaat conditionss such as Alzh
heimer’s diseease and
Parkinson’ss disease witth stem cellss.
8 Prokaryoticc cells have ribosomes,
r a cell wall, a cell
c membraane, a nucleo
oid region, an
nd, in most cases,
c plasmiids.
These simp
ple cells dividde by binary fission.
9 DNA existss in the nucleeoid region of
o prokaryotic cells. It is ccircular in forrm and is nott associated with protein
ns.
10 Membranee-bound orgaanelles, inclu
uding a nucleeus, are asso
ociated with eukaryotic
e cells.
11 Eukaryotic cells exhibitt much moree compartme entalization than
t prokaryyotic cells. Th
his allows certain areas to
o
carry out specialized annd highly effficient functio
ons. Organelles best dem
monstrate this compartm mentalizationn,
and includee mitochond dria, chloroplasts, nuclei, vacuoles, Golgi apparatus, endoplassmic reticulum, and
lysosomes..
12 The eukaryyotic cells of animals contain centriolles, while thee eukaryotic cells of plan
nts do not. Plant cells
contain chloroplasts, animal cells d
do not. Plant cells have ceell walls, anim
mal cells do not. Plant ceells have largger
han animal cells.
vacuoles th c
13 Cell membbranes includ
de phospholipids and pro
oteins. Thesee proteins maay be classified as integraal or
peripheral,, depending on their locaation.
14 The hydrop
phobic and hydrophilic
h p
properties of the cell mem
mbrane are the
t result of the chemicaal nature of the
t
phospholip
pid bilayer.
15 Examples o of passive traansport, which does not require any cellular enerrgy, include diffusion,
d faccilitated
diffusion, and
a osmosis.. Examples of h does requirre the expenditure of cellular energy,
o active transport, which
include enddocytosis, exxocytosis, an
nd the sodium
m–potassium m pump.
16 It is essential that the plasma
p mem
mbrane has a degree of flu
uidity so that shape chan
nges can occcur to allow
endocytosiis and exocyttosis.
© Peaarson Educatio
on Ltd 2013. For
F more information abou
ut the Pearson
n Baccalaureatte series pleasse visit
www.peearsonbacconline.com
,17 ‘Concerns’ of the cell th
heory include the multin nucleated cellls of muscle cells, fungall hyphae, and
d some greeen
o, the charactteristics of viruses raise some
algae. Also s questioons concerning cell theory. The ‘first’ cell always
presents a problem forr the cell theory.
18 At present,, the endosyymbiotic theo ory is the moost accepted explanation n for the development off eukaryotic
cells from p
prokaryotic cells.
c This theory states that,
t about 2 billion yearrs ago, a bactterium took up residencee
inside a very simple eukaryotic cell. The theoryy goes on to ssay that this was the firstt step in the developmennt
of the orgaanelles we seee today in eeukaryotic ceells.
19 Cell division allows the production of two identtical daughteer cells. Cell division
d invo
olves both miitosis, a nuclear
division, annd cytokinesis, a cytoplassmic division
n.
20 Cancer invo
olves cells whose
w cell cyccles are out of
o control. Mutagens,
M on
ncogenes, an
nd metastasiss are all term
ms
commonly associated with
w cancer.
21 Cyclins aree a group of proteins
p thatt control a ce
ell’s progresssion through
h the cell cycle. The cell cycle involvess
interphasee, in which th
he cell is busyy carrying ouut the functioons for which
h it is designated through
differentiation. Metabo olic activitiess such as pro
otein synthessis, DNA repllication, and organelle reeproduction
occur in this phase. Interphase includes the smaller phases known as G1, S, and G2.
22 The four sttages of mito
osis are prop
phase, metap
phase, anaphhase, and telophase. During prophasee and
metaphasee the chromo osome is actually two mo
olecules of DNA
D attached d together att the centrom
mere. Each
molecule of
o DNA is callled a chromaatid.
23 The DNA in n the nucleuss of eukaryotic cells goess through a process
p called supercoilin
ng to form th
he
chromosom mes that entter into mitosis. This supeercoiling invo
olves DNA wrapping
w around sphericaal proteins
called histo
ones to form
m nucleosomees.
© Peaarson Educatio
on Ltd 2013. For
F more information abou
ut the Pearson
n Baccalaureatte series pleasse visit
www.peearsonbacconline.com
, Chapter 2: Molecular biology
1 Living organisms and the cells that comprise living organisms are a complex set of interacting chemicals and
chemical reactions.
2 Water molecules are polar and thus have a relatively negative end (where oxygen is located) and a relatively
positive end (where the hydrogens are located).
3 Many of the properties of water are explained by its polarity. These properties include being a solvent for
other polar molecules, cohesion between water molecules, and also a variety of thermal properties.
4 Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen at or near the ratio of
CnH2nOn, where n = the number of carbon atoms.
5 The ‘building blocks’ of large organic molecules are often called monomers. Think of the smallest
carbohydrates (or monomers) as being ‘single sugar units’. Monosaccharides are single sugar units,
disaccharides are two-sugar units and polysaccharides are many sugar units in size. Lipids are also known as
fats and oils. A typical lipid, called a triglyceride, is composed of one molecule of glycerol bonded to three
molecules called fatty acids. Proteins are molecules composed of many amino acids bonded together.
6 Condensation reactions covalently bond smaller organic molecules together to form larger organic molecules.
Hydrolysis reactions reverse this by breaking the larger organic molecules apart into the original smaller
molecules.
7 The building block units of DNA molecules are called nucleotides. Each nucleotide is composed of a
monosaccharide sugar, a phosphate group, and one of four possible nitrogenous bases (adenine, thymine,
cytosine, or guanine).
8 DNA is composed of two strands of nucleotides. These two strands are held together by hydrogen bonding
between complementary bases. Together, they form an overall double helix geometric shape.
9 The complementary base pairs of DNA are:
• adenine and thymine
• cytosine and guanine.
10 DNA replicates in a semi-conservative pattern in which each of the two strands of DNA is used as a template
for the formation of a new strand. Thus, all newly formed DNA molecules are actually one half old DNA and
one half new DNA.
11 Proteins are synthesized using a two-step process. First, a strand of DNA is used as a template to create an
messenger (m)RNA molecule in a process called transcription. Second, this mRNA molecule, with the help of a
ribosome, transfer (t)RNA, and amino acids, synthesizes the actual protein in a process called translation.
12 The genetic code is written in sequences of three bases along the DNA molecule. Each sequence of three
bases is called a triplet.
13 Some proteins act as organic catalysts within cells and are called enzymes. Each enzyme typically has a single
substance that it is ‘specific for’ and that substance is called the enzyme’s substrate. As enzymes are complex
proteins, they are affected by variation in temperature, pH, and substrate concentration.
14 Cell respiration is common to all cells and explains how a cell derives energy in the form of ATP molecules
using organic molecules, such as glucose, as a fuel. Some cells use a relatively inefficient form of cell
© Pearson Education Ltd 2013. For more information about the Pearson Baccalaureate series please visit
www.pearsonbacconline.com
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