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Conferences Courses
Physics 982-003-50(Conted)
Brian’s Bio
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8. Order: living things are made up of
cells
Bacterial cells
Human bone cells
Plant cells
Single celled protist Cells are the basic unit of life
9. Order
Each cell has internal order & the cells within the
body have specific arrangements & functions
10. Cell theory: fundamental
principle in biology
1. a cell is the smallest unit of life
2. cells make up all living things
3. new cells arise from pre-existing cells
11. The Cell:
cells
as
fundamental molecules
to biology as
atoms
the atom is to tissues
chemistry
organ
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12. Cell Size
Prokaryotes
Most neurons
in µm range
Eukaryotes
13. Limitations to Cell size
Cell size – variable
small : 8 to 100 um
1 meter = 1000 mm
= 1 000 000 um
Larger organisms do not generally have larger cells
than smaller organisms—simply more cells.
Why so small?
14. Limitations to cell Size: homeostasis
• Oxygen required
• Waste products are released – must be removed from cell
• Exchanges food, gases, nutrients takes place through cell
surface
cell size metabolic needs
• As a cell becomes larger, its volume increases at a
greater rate than its surface area (plasma membrane)
15. Cell Size limited by :
• Cell surface area (plasma membrane)
• Surface area-to-volume ratio
• Metabolic demands: determined by volume
• But the transport of materials into or out of the cell is
determined by surface area
Volume increases
faster than surface
area
16. Surface area / Volume Ratio
• Small objects have large surface area to
volume ratio
• Cells – small lots of surface area
Ex:
17. Things all Cells have in Common
• surrounded by a membrane
• internal mass (cytoplasm)
• contain genetic information (DNA)
• have ribosomes (protein synthesis)
18. Two Major Types of Cells
• Prokaryotic cells
– Domain: Bacteria and Archaea
– No nucleus
– Lack most organelles
• Eukaryotic cells
– Domain: Eukarya
– Nucleus present in each cell
– Organelles present
19. Eukaryotic cell vs. Prokaryotic cell
DNA
(no nucleus)
Membrane
Membrane
Cytoplasm
Virus
Organelles
Nucleus (contains DNA) 1 µm
20. Prokaryotic cells
• DNA – free in cytoplasm
• ribosomes
• outer capsule (sugar or protein)
• cell wall
Cytosol (fluid)
22. Eukaryotic Cell
-Typically larger
- Contain internal membranes that form organelles
(more complex)
- DNA in membrane bound nucleus
ex: plant and animals
23. Plasma Membrane
A cell is surrounded by Plasma Membrane
- boundary between cell contents
and surroundings
- everything that enters/leaves
cell passes through cell
membrane
- divides cells into compartments
Why would me want to separate internal and external environments?
24. Structure of Plasma Membranes
Two components:
1. Phospholipid molecules
2. Protein molecules
26. Phospholipid Molecules
• One end attracted to water (Head)
• One end repelled by water (Tail)
When placed in water:
- they self assemble into a bi-
layer (double layer)
- shield hydrophobic portions
27. Cell organization & Size
- to maintain homeostasis: cell
contents separated from external
environment
plasma membrane
Phospholipid bi-layer
(Proteins not shown)
Cell Membrane:
- Selectively permeable: it allows some
substances to cross it more easily than others
28. Cytoplasm & Cytosol
• Cytoplasm: region between the nucleus and the
plasma membrane
• Cytosol: semifluid substance within the
membrane
– contains the organelles (makes up most of
the cell mass)
- Therefore; the cytoplasm
is filled with cytosol
30. Nucleus:
Contains DNA + Protein
• Chromatin: loosely arranged
DNA and Protein
• Chromosomes: tightly packed
Contains Nucleolus: Not membrane bound
makes ribosomes
31. The Cell’s Heritable
Information
- All cells contain deoxyribonucleic acid
(DNA)
= heritable material that directs the
cell’s activities.
Inherited DNA Directs
development of an organism
32. Information Transfer
- Living things must have a set of instructions that
allow them to grow, develop, respond to stimuli,
reproduce…
- those ―instructions‖ are found in DNA
- blueprint for all cellular activities
- DNA made up of genes
- Genes are the units of inheritance
that transmit information from parents
to offspring.
33. Four main classes of biological
molecules
1.Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids
34. Organic Compounds
• Contain carbon (C backbone)
• Most contain H and O
• May contain other elements
N = Nitrogen
P = Phosphorus
S = Sulfur
35. Why is Carbon Special?
Carbon can form 4 covalent bonds
– bonds with up to 4 separate atoms
– can bond with other C atoms
long chains of carbon atoms
can combine with many other kinds of atoms
37. Distinctive properties of an organic molecule
depends on:
1) Arrangement of carbon skeleton
2) Functional
groups
= molecular
components
attached to that
carbon skeleton)
• Give molecule
distinctive
chemical
properties
40. Biological molecules are composed of subunits that
are linked to each other
• Single unit = monomer
(pearl)
• Chain or ring of of monomers
= polymer
(pearl necklace)
41. Synthesis and Breakdown of Polymers
• Synthesis
–Addition of subunits chain grows
• Breakdown
–Removal of subunits chain
shortens
43. Condensation or Dehydration synthesis is the
chemical reaction that links repeating subunits
together.
When dehydration synthesis occurs, a bond forms
and WATER is released.
Result:
• Increase in ―chain‖
• molecule of water
released
46. Nucleic acids
Purpose:
- Store and transmit hereditary information
in Genes = units of inheritance
- Program amino acid sequence of Proteins
Made of nucleotides
47. Types
1. Deoxyribonucleic acid (DNA):
Stores information for protein synthesis
2. Ribonucleic acid (RNA):
Directs protein synthesis
48. Structure
– Consists of building blocks called nucleotides
Nitrogenous
i) phosphate molecule (P) base
O 5’C
ii) 5-carbon sugar (S) O P O CH2
O
O
iii) nitrogenous base (B) Phosphate
3’C
group Pentose
sugar
Nucleotide
49. Fig. 5-27ab
Structure
Nucleoside
Nitrogenous
Nitrogenous
base
base
O 5'C
5’C
O P O CH2
O
O
Phosphate
Phosphate
3’C
3'C
group
group Pentose
Sugar
5'C sugar
(pentose)
(b) Nucleotide
3'C
3' end Nucleotides form chains
(a) Polynucleotide, or nucleic acid called polynucleotides
50. Structure
Nucleotide = building block
Nucleic acid = chain
52. DNA and RNA –
4 POSSIBLE NUCLEOTIDES FOR EACH
DNA RNA
53. DNA
• Needed for cell replication
• Contains genes
• Genes tell cells which
proteins to make
• Complementary base
pairing Hydrogen bond
The sequence of bases along a nucleotide
polymer is unique for each gene
J Watson & F Crick Cambridge University; 1953
54. DNA Assembly
P P Bases:
S – B -- B - S Adenine (A)
P P Guanine (G)
S - B -- B - S Cytosine (C)
Thymine (T)
P P
S - B -- B - S
P P 2 strands held together by
S - B -- B - S hydrogen bonds between
the paired bases
55. Complementary Base Pairing
In DNA:
A and T
C and G
– always line up together!
Referred to as complementary
base pairing
56. DNA Assembly
P P
S– A -- T -- S
P P
S -- G -- C --S
P P
S -- C -- G -- S
P P
S -- T -- A -- S
57. Summary: DNA
• DNA contains
the genetic code
• DNA contains
―blueprint‖ for
making different
proteins
DNA over 2m long!
58. The way DNA encodes a cell’s
information is analogous to the way we
arrange the letters of the alphabet
RAT =
ART=
Sequence in letters = changes in meaning
Sequence of nucleotides = different proteins
59. Genetic Information
• Each gene carries information needed to make a
specific PROTEIN
• Genes carry information that determines the
primary sequence of the protein
Protein synthesis
61. Proteins
Proteins account for 50% of the organic matter in a typical animal
body, and they play a critical role in almost all life processes
62. Proteins
• Proteins are made of amino acids.
• There are 20 common a.a.
• Polypeptide: chain of a.a.
• Protein: 1 or more polypeptides
folded/coiled into a specific shape
63. Amino Acids -
building blocks of proteins
• All amino acids have same basic skeleton:
Carboxyl group
R group - variable
64. Essential Amino Acids
• Animal cells can make some, but not all
amino acids
• Essential a.a.: those that we can’t make
or make enough of to meet our needs.
– Required from diet
Asparagine Ammonia (pee) and Oxaloacetate
Asparagusic Acid Methylmercaptan
66. Protein = chain of amino acids
Synthesis reaction
As the chain grows you
create a polypeptide
67. Structure
• very complex
– large variety of amino acids
– very large
– different protein molecules have
their own distinct shape
68. 4 levels of structure
• Primary
• Secondary
• Tertiary
• Quaternary
• Polypeptide can spontaneously organize
into complex shapes (change)
• Protein shape essential to function
– Ex receptor, antibody, enzyme
74. A very important protein: Ribosome
• Uses RNA to make other proteins
• Made in the nucleolus
75. Conformation: determines function
- single amino aid substitution
76. Denaturation
- when a protein unravels and loses its
native conformation
Denaturation
Normal protein Denatured protein
Renaturation
77. Recall… Protein
Structure
• For cell to reliably make proteins, it must be able
to control the placement of animo acids
• Each protein has its own
unique primary sequence!
Proteins are complex
–made up of building blocks called amino
acids
–20 different kinds
–number and sequence of the aa’s =
primary sequence controls shape
function
78. How does the Information on the
DNA Molecule get Converted into a
Protein?
• DNA not used directly
• Involves various forms of RNA (the other nucleic acid)
• Accomplished by a process called:
PROTEIN SYNTHESIS
79. DNA
P S
ro 1 Synthesis of
Transcription y
te mRNA in the
nucleus mRNA nt
in h
NUCLEUS e
CYTOPLASM
si
mRNA
2 Movement of s
mRNA into cytoplasm Ribosome
via nuclear pore
3 Synthesis
of protein
Translation
Amino
Polypeptide acids
80. 2 major steps in protein synthesis
1) Transcription (information storage)
DNA RNA
2) Translation (information carrier)
RNA Protein
(product)
83. Transcription of a Hypothetical Gene:
a) Separation of DNA
ATG GGA TTT AAC CCT GGA GGG TAA
* TAC CCT AAA TTG GGA CCT CCC ATT**
- Two strands separate in region of gene
ATG GGA TTT AAC CCT GGA GGG TAA
XXXX XXXXXX
XXXX XXXXXX
**TAC CCT AAA TTG GGA CCT CCC ATT **
**coding strand
84. Transcription: b)
Synthesis of mRNA
Synthesis of an RNA molecule that is complementary to
the DNA (following the base pair rule)
DNA mRNA = This molecule is called messenger RNA
85. Transcription: b)
Synthesis of mRNA
(DNA) XXXX ATG GGA TTT AAC CCT GGA GGG TAA XXXXXX
(mRNA) AUG GGA UUU AAC CCU GGA GGG UAA
(DNA)XXXX TAC CCT AAA TTG GGA CCT CCC ATT ** XXXX
DNA: A T C G
RNA: U A G C
86. Summary of Transcription and
Release of completed mRNA molecule
enzyme
Once the mRNA
molecule is
complete the
transcription
process is over
87. • Transfer of information from DNA to
mRNA completes first phase of protein
synthesis (Transcription)
Next question:
How is the information in mRNA used to
make a protein?
88. What information do we have?
mRNA: AUG GGA UUU AAC CCU GGA GGG UAA
Need to:
convert nucleic acid language (in the
mRNA) into amino acid language
(protein)
89. Step 2:
Translation Amino
Polypeptide acids
Translation = tRNA with
amino acid
Assembly of the Ribosome
attached
protein primary
structure
according to tRNA
instructions Anticodon
(codon sequence)
on the mRNA 5 Codons 3
mRNA
90. Translation mRNA Protein
• information on mRNA is contained in groups of 3
nucleotides called CODONS
mRNA: AUG GGA UUU AAC CCU GGA GGG UAA
• Codons on mRNA provide the sequence or
order in which the amino acids must be
arranged to create the primary structure of
the protein
• mRNA has the information but doesn’t do the
work
91. Translation
In example: 8 codons
AUG GGA UUU AAC CCU GGA GGG UAA
Amino Acids are not nucleic acids – so they have nothing to do
with the base pair rules
The cell needs a way to match up amino acids with the 3 letter
codons on the mRNA….
translation requires a second type of RNA
called transfer RNA (tRNA)
93. Translation
Transfer RNA (tRNA):
Anticodon
aa
ANTICODON
= group of 3 Nucleotides
complementary to CODONS on mRNA
In example anticodon is AAG
- AAG (ANTICODON) would pair with
CODON UUC on a mRNA molecule
94. Translation
Transfer RNA (tRNA):
Amino Acids
At other end aa
Attachment site for 1
AMINO ACID molecule
Recall…
there are 20 aa
How many codons are
there?
95. Translation
Many Kinds of tRNA
Each kind is unique in that:
1. it has a unique ANTICODON
2. Each can attach 1 (and only 1 kind) of
AMINO ACID (aa)
96. Translation
Each codon site on mRNA:
- has only 1 ANTICODON that can bind to it
- the tRNA with the appropriate anticodon can
only transport 1 kind of amino acid
- Therefore only one aa aa aa
kind of amino acid can
be placed at a particular
codon site
Codons on mRNA
97. Translation
Example
• Suppose a mRNA:
– UUU UUU UUU UUU UUU
• What tRNA can be used?
• How many amino acids are in the protein?
• What amino acids are they?
98. Translation
Codons for Amino Acids
(on the mRNA)
• MANY amino acids have
several CODONS
64 possible anticodons:
• 1 start (met), 3 stop
• 61 anticodons code for
amino acids
101. Translation
Role of tRNA
• Positions each amino acid in its proper
order in the amino acid chain as
determined by the sequence of codons
in the mRNA molecule
• Each tRNA has a unique anticodon and it
carries only 1 kind of amino acid
102. Translation
Ribosomes (= Protein + rRNA)
• Attach to start end of mRNA
• As tRNAs attach to mRNA the ribosome
begins to move along mRNA molecule
• As it does, it aligns first 2 aas which are then joined
together by an enzyme
• Repeats by aligning & joining aa# 3 to aa#1+2 so they
can be joined and so on
• When it reaches the end of mRNA molecule the aa chain
is released into cytoplasm
107. Mutation & Sexual Recombination Produce
Genetic Variation
• New genes and new alleles originate only by mutation
• A mutation is a change in the nucleotide sequence of an
organism’s DNA.
• Most mutations occur in somatic cells and are lost when the
individual dies.
• Only mutations in gametes can be passed on to
offspring, and only a small fraction of these spread through
populations and become fixed.
Mutations = changes in the
nucleotide sequence of DNA
Cause new genes and
alleles to arise
108. Mutation rates
– Tend to be low in animals and plants
– Average about one mutation in every
100,000 genes per generation
– Are more rapid in microorganisms
109. REVIEW:
Step 1. Coding strand:
DNA: GCTACGCTCAATGGGTCGAGCCTATT
RNA: CGAUGCGAGUUACCCAGCUCGGAUAA
- what is this step called?
- what kind of RNA did you make?
110. REVIEW:
mRNA: CG AUG CGA GUU ACC CAG CUC GGA UAA
(Start) Arg- Val- Thr- Gln - Leu – Gly (stop)
- steps involved?
-Types of RNA?
Codon on mRNA
Trp
aa on tRNA
111. REVIEW:
Transcription base pair rule mRNA
codons on mRNA decoded by
Translation tRNA
ribosomes (rRNA) help in aa
assembly to make the protein
112. REVIEW:
Gene 2
DNA
molecule
Gene 1
Gene 3
DNA
template
strand
TRANSCRIPTION
mRNA
Codon
TRANSLATION
Protein
Amino acid
