molecular components of cells
TRANSCRIPT
![Page 1: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/1.jpg)
Molecular Components of
Cells
Chapter 3
![Page 2: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/2.jpg)
Molecular Components of Cells
Chemical composition
C, H, O, N and small amount of other elements
Molecular building blocks
Lipids
Carbohydrates
Proteins
Nucleic acids
• DNA
• RNA
Water (70-80%)
Protein
Carbohydrate,
Lipid,
Nucleic acid
![Page 3: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/3.jpg)
Atoms, Ions, and Molecules
Atoms
Biologically important atoms
---- C, H, O, N, S, P, Na, K, Ca, Cl
Ions
Biological importance: electrical impulse, ion balance
• Ca2+, Na+, K+, Cl-
Molecules
Generated from chemical bonding of atoms
![Page 4: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/4.jpg)
Subunits of Biological Molecules
Class of Molecules Examples Repeating Unit
Lipid Fats, oils Glycerol, fatty acid
Carbohydrate Sugars, starch,
cellulose
Simple sugars
Nucleic acid DNA, RNA Nucleotide
Proteins Enzymes Amino acids
![Page 5: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/5.jpg)
Lipids
Hydrophobic fats, oils, and cholesterol etc.
High energy C-H, C-C bonds good energy storage
Fats : glycerol + fatty acids
Triglyceride
![Page 6: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/6.jpg)
Lipids
Fatty acid Saturated: tight packing solid at room temperature
Unsaturated: more than one cis-double bond liquid
![Page 7: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/7.jpg)
Lipids
Phospholipid Major component of cellular membrane
Glycerol backbone
two fatty acids (hydrophobic)+ phosphate (hydrophilic)
![Page 8: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/8.jpg)
Lipids
Sterols
Cyclic hydrocarbon compounds
Cholesterol
• Component of animal cell membranes
– decrease membrane fluidity
• Starting material for steroid hormones and bile synthesis
![Page 9: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/9.jpg)
C : H : O = 1 : 2 : 1
Simple sugars (monosaccharide)
Disaccharide
sucrose (glucose + fructose)
lactose (galactose + glucose)
Polysaccharide
pectin, starch, cellulose --- from glucose
agar, carrageenan (thickener for ice cream)
Carbohydrates
![Page 10: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/10.jpg)
Linear and Ring Structure
Monosaccharide may be present in the form of
a linear or ring structure.
In solution, it is in the form of a ring structure.
![Page 11: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/11.jpg)
Mono- and Disaccharides
OH
(a form) (b form)
1 2
1 2
a
b
(a form)
a b
b
1 4
1
CH2OHI
![Page 12: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/12.jpg)
Polysaccharides
Amylose (a-1,4-Glycosidic linkage)
Cellulose (b-1,4-Glycosidic linkage)
![Page 13: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/13.jpg)
Polysaccharides
Amylopectin (branched chain, a-1,6-Glycosidic linkage)
![Page 14: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/14.jpg)
Roles of Carbohydrates I
Carbohydrates in energy metabolism
Plant
• Glucose synthesis by photosynthesis
6CO2 + 6H2O + energy C6H12O6 + 6O2
• Starch for energy storage
• cellulose for structural compound
Animals
• Intake glucose from food
• Glycogen for energy storage
![Page 15: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/15.jpg)
Roles of Carbohydrates II
Carbohydrates in molecular recognition Often found connected to other molecules on the outsides of
cells --- cellular recognition, cell signaling, cell adhesion
e.g. blood typing : sugar chains in the membrane of RBC
![Page 16: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/16.jpg)
Proteins
Roles of proteins Most of the cellular functions
• Enzymes : chemical reactions
• Receptors : signal transduction
• Antibody : recognition of foreign molecules and trigger
immune responses
• Transporters : e.g. hemoglobin for oxygen
• Structural proteins : keratin (hair and nails), actin and myosin
(muscle)
Diversity of organism• Due to the organization of proteins within an organism
---- particularly structural proteins and those that synthesize
additional structural body components
![Page 17: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/17.jpg)
Proteins
Amino acids
Building blocks of proteins
Hydrophilic backbone + 20 side
chains
Polypeptide
Amino acid chains linked by
peptide bond
Three-dimensional structure
Determines protein function
Determined by amino acid
sequence
![Page 18: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/18.jpg)
Nucleic acids
Nucleotides
Building blocks of nucleic acids
(deoxy)ribose + phosphate group +
4 bases
Bases: adenine (A), guanine (G),
cytosine (C), thymine (T)
Terminology
Base
Nucleoside : sugar + base
Nucleotide : sugar + base
+ phosphate
o
OH
![Page 19: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/19.jpg)
Primary Structure : Nucleotides
H
Adenine
Guanine
Cytosine
Thymine (D)
Uracil (R)
RNA DNA
Base
2’-Deoxyribose
Nucleoside
Adenosine
Guanosine
Cytidine
Thymidine
Uridine
Nucleotide
Adenylate
Guanylate
Cytidylate
Thymidylate
Uridylate
Purine
Pyrimidine
![Page 20: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/20.jpg)
AMP, ADP, ATP
AMP = Adenylate
(cf. dAMP) OH
OH
OH
![Page 21: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/21.jpg)
Nucleotide Chains
Linkage of 5’ carbon to 3’ carbon through
phosphodiester bond
![Page 22: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/22.jpg)
Nucleotide Chains
Base pairing
C=G, T=A : hydrogen bonding
Complementary base pairs
Antiparallel strand in DNA
molecule
![Page 23: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/23.jpg)
Chromosome
Tightly packed complex of DNA and histone proteins
![Page 24: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/24.jpg)
DNA Replication
Synthesis of a complementary strand using the other strand as a
template
DNA polymerase
![Page 25: Molecular Components of Cells](https://reader031.vdocuments.us/reader031/viewer/2022012915/61c5e6812a43fc18f51d1ed3/html5/thumbnails/25.jpg)
Expression of Genetic Information
Replication
Transcription
DNA
mRNA
Translation
Protein