Sarah’s Biology Study Guide 2021
Unit 1 Cell Biology
1.1 Introduction to cells
Cell Theory
1. Living organisms are composed of cells
2. Cells are the smallest unit of life
3. Cells come from pre-existing cells
Atypical cell
a) Striated muscle fibre: challenge the idea that a cell has one nucleus, it is multinucleated. Also the fibre
is abnormal in its size compared to normal cells.
b) Giant Algae: challenges the idea that a cell has simple structure and is small in size, it is a big
single-cell organism and has sophisticated structures.
c) Aseptate Fungi hyphae: challenges the cell theory by having shared cytoplasm, multinucleated, and
large in size.
Magnification
Resolution = measure of clarity of the image
- Higher resolution, more clarity.
Electronic microscopes
SEM (scanning electron) microscopes; outer
TEM (transmission election) microscopes; inner
𝑓𝑎𝑘𝑒 𝑠𝑖𝑧𝑒 𝑆𝑖𝑧𝑒 𝑜𝑓 𝑡ℎ𝑒 1000 nm (nanometer) = 1μm (micrometer)
𝑀𝑎𝑔𝑛𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛 = 𝑟𝑒𝑎𝑙 𝑠𝑖𝑧𝑒
= 𝐴𝑐𝑡𝑢𝑎𝑙 𝑆 1000μm (micrometer) = 1 mm (millimeter)
,Function of life in a cell
Homeostasis Maintenance of a constant internal environment by regulating internal cell conditions
Metabolism Regular set of life-supporting chemical reactions that takes place within the cells of living
organisms
Nutrition Intake of nutrients, different forms in different organisms. (autotrophic/heterotrophic)
Growth Increase in size or shape that occurs over period of time
excretion Removal of waste products of metabolism and unimportant materials from an organism
response A reaction by the living organism to changes in the external environment
reproduction Production of offspring (sexualy or asexually) to pass genetic information to the next
generation.
Functions of life in Paramecium and one named photosynthetic unicellular organism
Paramecium: unicellular protozoa. Heterotrophs living in aquatic environments.
Homeostasis A constant internal environment is maintained by collecting excess water in the contractile
vacuoles and it is expelled through the plasma membrane (osmoregulation).
Metabolism Most metabolic reactions are catalyzed by enzymes and take place in the cytoplasm
Nutrition Heterotroph, engulfs food particles in vacuoles where digestion takes place. Soluble products
are absorbed into the cytoplasm of the cell. (microorganisms, bacteria, algae, etc.)
Growth As it consumes food, the paramecium enlarges. Once it reaches a certain size it will divide
into two daughter cells
excretion Digested nutrients from food vacuole pass into the cytoplasm and reaches the anal pore,
expelling its waste to the external environment.
response The wave action of the beating cilia helps to propel Paramecium in response to changes in
the environment.
reproduction Carry both sexual and asexual reproduction. Latter is more common. It goes through binary
, fission.
Surface area to volume ratio in relation to limiting cell size
Surface area: determine the rate of exchange of materials within the cell membrane
Volume: determines the level of metabolic activity in the cell
- Small organisms (have larger SA relative to its volume): diffusion is effective
- Big organisms (have smaller SA relative to its volume): diffusion is ineffective
+ Volume increases at a faster rate than surface area.
*Therefore...Cell size is limited by diffusion capability.
Properties that emerge from the interaction of their cellular components in multicellular organisms
a) Differentiation = process of unspecialized cell developing into specified functions and structures
b) Emergent properties, interaction between differentiated parts of multicellular organisms enable other
activities unicellular organisms cannot perform.
[state] Regulation of gene expression
Genome = complete set of genes, chromosomes or genetic material present in a cell
- When a cell goes through differentiation, only certain genomes are switched on to develop special
functions and structures.
Division and differentiation of stem cells
Stem cells = undifferentiated cell of a multicellular organism that have potential to turn into a great different cell
types (pluripotent-many/totipotent-any)
- Ability to divide multiple times
- Ability to differentiate into different types of cells
Types of stem cell in embryonic development → suitable for therapeutic uses
Types of Stem cells
Embryonic stem cell Pluripotent(any)
(of the blastocyst) - Potentially be cultured to provide renewable source of cells of research
- Totipotent embryonic stem cell is the first cell formed during fertilization.
(morula)
Umbilical cord blood Pluripotent (many)
stem cell - Obtained from umbilical cord
(adult stem cell) - Can give rise to a more limited number of cell types
Bone marrow stem Can become white/red blood cells
cells - Obtained from bone marrow or spine.
(adult stem cell) - Can give rise to a more limited number of cell types
Therapeutic use of stem cells (Stargardt’s disease/Leukemia/Parkinsons’ disease)
, Stargardt’s disease Macular degeneration, progressive loss in central vision.
Cause: recessive genetic mutation in certain genes that malfunctions active
transport protein on photoreceptor cells.
Treatment: embryonic stem cells are injected to the retina, developing into one of
retina cells. This becomes functional restoring vision.
Leukemia Type of cancer in blood or bone marrow
Cause: abnormally high numbers of white blood cells which increases risks of
developing infections, anemia, and bleeding.
Treatment: collect multipotent stem cells from bone marrow or umbilical cord blood
and is transplanted to the patient's bone marrow after the patient has undergone
chemotherapy to eliminate diseases WBC.
Ethics of the therapeutic use of stem cells.
- The process of obtaining a totipotent stem cell involves destruction of an embryo which raises
controversy. (moral rights/IVF)
1.2 Ultrastructure of cells
Simple cell structure and compartmentalisation of Prokaryotes
- Primitive, simple cell structure (unicellular,
small) with no membrane bound nucleus &
organelles
Structures
Nucleoid (with circular DNA): control all cell activity
Plasmids: DNA carrying few genes
Cytoplasm: site of all metabolic reaction
ribosomes (70S): protein synthesis
cell wall: enclose, protect, shape the cell
plasma membrane: control movement within the cell
Pili: adhesion and DNA transfer between cells
Flagellum: locomotion of cell
Asexual binary fission
a) Chromosomes replicated
b) Two copies of DNA move to opposite ends of the cell
c) Cell grows longer (elongates)
d) Plasma grows inward and separates into genetically identical cells (=haploid)
Compartmentalized cell structure of Eukaryotic cells
- Include Protists, Fungi, Plantae, and Animalia.
Compartmentalization = formation of compartments within the cell by membrane-bound organelles
Advantages
- Efficient metabolism (enzymes and substrates are concentrated, faster reaction)
- Internal conditions (pH) can be differentiated; maintain optimal condition
Unit 1 Cell Biology
1.1 Introduction to cells
Cell Theory
1. Living organisms are composed of cells
2. Cells are the smallest unit of life
3. Cells come from pre-existing cells
Atypical cell
a) Striated muscle fibre: challenge the idea that a cell has one nucleus, it is multinucleated. Also the fibre
is abnormal in its size compared to normal cells.
b) Giant Algae: challenges the idea that a cell has simple structure and is small in size, it is a big
single-cell organism and has sophisticated structures.
c) Aseptate Fungi hyphae: challenges the cell theory by having shared cytoplasm, multinucleated, and
large in size.
Magnification
Resolution = measure of clarity of the image
- Higher resolution, more clarity.
Electronic microscopes
SEM (scanning electron) microscopes; outer
TEM (transmission election) microscopes; inner
𝑓𝑎𝑘𝑒 𝑠𝑖𝑧𝑒 𝑆𝑖𝑧𝑒 𝑜𝑓 𝑡ℎ𝑒 1000 nm (nanometer) = 1μm (micrometer)
𝑀𝑎𝑔𝑛𝑖𝑓𝑖𝑐𝑎𝑡𝑖𝑜𝑛 = 𝑟𝑒𝑎𝑙 𝑠𝑖𝑧𝑒
= 𝐴𝑐𝑡𝑢𝑎𝑙 𝑆 1000μm (micrometer) = 1 mm (millimeter)
,Function of life in a cell
Homeostasis Maintenance of a constant internal environment by regulating internal cell conditions
Metabolism Regular set of life-supporting chemical reactions that takes place within the cells of living
organisms
Nutrition Intake of nutrients, different forms in different organisms. (autotrophic/heterotrophic)
Growth Increase in size or shape that occurs over period of time
excretion Removal of waste products of metabolism and unimportant materials from an organism
response A reaction by the living organism to changes in the external environment
reproduction Production of offspring (sexualy or asexually) to pass genetic information to the next
generation.
Functions of life in Paramecium and one named photosynthetic unicellular organism
Paramecium: unicellular protozoa. Heterotrophs living in aquatic environments.
Homeostasis A constant internal environment is maintained by collecting excess water in the contractile
vacuoles and it is expelled through the plasma membrane (osmoregulation).
Metabolism Most metabolic reactions are catalyzed by enzymes and take place in the cytoplasm
Nutrition Heterotroph, engulfs food particles in vacuoles where digestion takes place. Soluble products
are absorbed into the cytoplasm of the cell. (microorganisms, bacteria, algae, etc.)
Growth As it consumes food, the paramecium enlarges. Once it reaches a certain size it will divide
into two daughter cells
excretion Digested nutrients from food vacuole pass into the cytoplasm and reaches the anal pore,
expelling its waste to the external environment.
response The wave action of the beating cilia helps to propel Paramecium in response to changes in
the environment.
reproduction Carry both sexual and asexual reproduction. Latter is more common. It goes through binary
, fission.
Surface area to volume ratio in relation to limiting cell size
Surface area: determine the rate of exchange of materials within the cell membrane
Volume: determines the level of metabolic activity in the cell
- Small organisms (have larger SA relative to its volume): diffusion is effective
- Big organisms (have smaller SA relative to its volume): diffusion is ineffective
+ Volume increases at a faster rate than surface area.
*Therefore...Cell size is limited by diffusion capability.
Properties that emerge from the interaction of their cellular components in multicellular organisms
a) Differentiation = process of unspecialized cell developing into specified functions and structures
b) Emergent properties, interaction between differentiated parts of multicellular organisms enable other
activities unicellular organisms cannot perform.
[state] Regulation of gene expression
Genome = complete set of genes, chromosomes or genetic material present in a cell
- When a cell goes through differentiation, only certain genomes are switched on to develop special
functions and structures.
Division and differentiation of stem cells
Stem cells = undifferentiated cell of a multicellular organism that have potential to turn into a great different cell
types (pluripotent-many/totipotent-any)
- Ability to divide multiple times
- Ability to differentiate into different types of cells
Types of stem cell in embryonic development → suitable for therapeutic uses
Types of Stem cells
Embryonic stem cell Pluripotent(any)
(of the blastocyst) - Potentially be cultured to provide renewable source of cells of research
- Totipotent embryonic stem cell is the first cell formed during fertilization.
(morula)
Umbilical cord blood Pluripotent (many)
stem cell - Obtained from umbilical cord
(adult stem cell) - Can give rise to a more limited number of cell types
Bone marrow stem Can become white/red blood cells
cells - Obtained from bone marrow or spine.
(adult stem cell) - Can give rise to a more limited number of cell types
Therapeutic use of stem cells (Stargardt’s disease/Leukemia/Parkinsons’ disease)
, Stargardt’s disease Macular degeneration, progressive loss in central vision.
Cause: recessive genetic mutation in certain genes that malfunctions active
transport protein on photoreceptor cells.
Treatment: embryonic stem cells are injected to the retina, developing into one of
retina cells. This becomes functional restoring vision.
Leukemia Type of cancer in blood or bone marrow
Cause: abnormally high numbers of white blood cells which increases risks of
developing infections, anemia, and bleeding.
Treatment: collect multipotent stem cells from bone marrow or umbilical cord blood
and is transplanted to the patient's bone marrow after the patient has undergone
chemotherapy to eliminate diseases WBC.
Ethics of the therapeutic use of stem cells.
- The process of obtaining a totipotent stem cell involves destruction of an embryo which raises
controversy. (moral rights/IVF)
1.2 Ultrastructure of cells
Simple cell structure and compartmentalisation of Prokaryotes
- Primitive, simple cell structure (unicellular,
small) with no membrane bound nucleus &
organelles
Structures
Nucleoid (with circular DNA): control all cell activity
Plasmids: DNA carrying few genes
Cytoplasm: site of all metabolic reaction
ribosomes (70S): protein synthesis
cell wall: enclose, protect, shape the cell
plasma membrane: control movement within the cell
Pili: adhesion and DNA transfer between cells
Flagellum: locomotion of cell
Asexual binary fission
a) Chromosomes replicated
b) Two copies of DNA move to opposite ends of the cell
c) Cell grows longer (elongates)
d) Plasma grows inward and separates into genetically identical cells (=haploid)
Compartmentalized cell structure of Eukaryotic cells
- Include Protists, Fungi, Plantae, and Animalia.
Compartmentalization = formation of compartments within the cell by membrane-bound organelles
Advantages
- Efficient metabolism (enzymes and substrates are concentrated, faster reaction)
- Internal conditions (pH) can be differentiated; maintain optimal condition
