Biology and Chemistry of Cells Lecture 1
BIOLOGY SUMMARY: BIOM1050 Biology for Health Sciences Module 1: Biology and Chemistry of Cells Lecture 1: A study of life and cells What is life? - living things can be recognised by what they do Living things: •Have order •Adapt to their environment •Respond to their environment •Regulate their cellular and body processes •Grow and develop •Reproduce Living things are organised into a biological hierarchy. The levels range from the whole planet to the molecules that make up our cells. - The biosphere - Ecosystems - Communities - Population - Organisms - Organs and Organ Systems - Tissues - Cells - Organelles - Molecules - Electrons Respiration is a biochemical process which produces/generates ATP from ADP and therefore energy (which we use to do work). The master molecule = DNA —-> nucleic acid (DNA and RNA) DNA - DNA = deoxyribonucleic acid - 4 bases (A, T, C, G) - DNA is a double stranded molecule • DNA constitutes the heritable information molecule in cells. • Genes are encoded on DNA. • Genes encode proteins. - Expression and activity of the proteins in your cells will direct your appearance and your behaviour. This is the same for all organisms.
RNA - 4 bases (G, A, U, C) - single stranded molecule - RNA often folds back on itself and that is how the strands are paired (A & U) (G & C) - Viruses have RNA genome - Our genes encode all the proteins necessary to make a human - Our DNA code contains large amounts of “non - coding or ‘junk sequences” —> the sequences that seem to have nothing in it often encodes RNA. This RNA is often used to regulate how the RNA is translated (turned on and turned off) - some organisms have 6 bases in the genetic code. However generally and for humans there are usually 5 bases Chapter 6: A tour of the cell Eukaryotic Cells have internal membranes that compartmentalise their functions Prokaryotic and Eukaryotic cells Prokaryotic: include bacteria and archaea Eukaryotic: include protists, fungi, animals and plants -
they are both bounded by a selective barrier called the plasma membrane they both have cytosol they both have chromosomes which carry genes in the form of DNA all cells have ribosomes which make proteins according to instructions from the genes the surface to volume ratio is an important parameter affecting cell size and shape. plant and animal cells have most of the same organelles: a nucleus, endoplasmic reticulum, Golgi apparatus, and mitochondria.
Differences: - in a eukaryotic cell most of the DNA is located in the nucleus which is bounded by a double membrane. In a prokaryotic cell the DNA is concentrated in a region that is not membrane encloses called the nucleoid. - Eukaryotic cells are often much larger The relationship between the nucleus and ribosomes: Nucleus: surrounded by a nuclear envelope (double membrane) perforated by nuclear pores; nuclear envelope continuous with endoplasmic reticulum (ER). The nucleus function is to house chromosomes which are made of chromatin (DNA and protein), contains the nucleoli, where ribosomal sub units are made, pores regulate the entry and exit of materials. Ribosome: two sub units made of ribosomal RNA, and proteins; can be free in cytosol or bound to ER. There function is protein synthesis.
The key role played by transport vessels in the endo-membrane system
Mitochondria and chloroplasts change energy form one form to another
The cytoskeleton is a network of fibres that organises structure and activities in the cell - the cytoskeleton functions in structural support for the cell and in motility and signal transmission - microtubules shape the cell, guide organelle movement and separate chromosomes in dividing cells. Cilia and flagella are motile appendages containing microtubules. Primary cilia also play sensory and signalling roles. Microfilaments are thin rods that function in muscle contraction, amoeboid movement, cytoplasmic streaming, and support of microvilli. Intermediate filaments support cell shape and fix organelles in place. Extracellular components and connections between cells help coordinate cellular activities - plant cell walls are made of cellulose fibres embedded in other polysaccharides and proteins - animal cells secrete glycoproteins and proteoglycans that form the extracellular matrix which functions in support, adhesion, movement and regulation - cell junction connects neighbouring cells. plants have plasmodia that pass through adjoining cell walls. Animal cells have tight junctions, desmosomes and gap junctions. Lecture 2 BIOM1050 Module 1: Biology and Chemistry of Cells A tour of cells How does information get from the DNA to the rest of the cell? - the DNA sequence encodes genes - genes encode proteins - proteins do work in the cells - too get from gene to protein, the cell produces an intermediate molecule called messenger RNA (mRNA) in a process called transcription - Transcription (TXN) —> process from changing RNA from DNA) - The cell then uses this mRNA to produce a protein in a process called translation (RLN making protein using mRNA template. There are lots of different types of RNA (mRNA,tRNA etc.)
Prokaryotic - naked DNA (packaged differently Less genetic material in a prokaryotic cell Prokaryotic and eukaryotic cells both have nuclei Nuclei acids = DNA and RNA Both prokaryotes and eukaryotes have nuclei acids What is in a prokaryotic cell? - ribosomes (ribosomes generally make protein) they are in the cytoplasm - carbohydrates - generate ATP using the cell membrane as they don't have a mitochondrion. - membranes - has a membrane around the outside - DNA - protein Module 1: Biology and Chemistry of Cells Lecture 3: The membrane
We can think of the cell as a ‘balloon’ of materials surrounded by a selectively permeable, protective membrane – but cell is not just simple balloon-shaped ball passively floating around
the cell is dynamic and the composition of the membrane differs, depending on the cell type. The plasma membrane: Functions of the cell membrane: - Encloses and Protects the Cell Contents. : The membrane forms a barrier between inside and outside of the cell. Different chemical environments can exist on each side of the cell membrane. The cell membranes are selectively permeable. They allow certain molecules through and block the movement of others. The membrane is made of things with a hydrophilic (outer) and hydrophobic (inner membrane) membrane. Note: sugar and proteins do not dissolve across a membrane. Small gases e.g. O2, CO2 dissolve across a membrane. small molecules (that are polar) disuse across a membrane e.g. CH4, small molecules with some polarity eg. ethanol and methanol dissolve across a membrane however not as well as CH4. Water also dissolves across a membrane however it is slow. Proteins, DNA and RNA, ions, protons, Na+, K+, CE-, H+ never diffuse across a membrane. Anything charged will not defuse across a membrane. The fact the membrane is semi permeable is crucial to the functioning. - proteins are used to actively transport (push things against a concentration gradient), send messaged from the inside and outside of the cell, provides structural strength to the membrane, allows passive transport. - this also happens on the membranes in the organelles e.g. the mitochondria membrane and chloroplasts. It is also still a double membrane 2. Provides and Supports Mechanical Structure: Cytoskeleton: Proteins in the cell membrane attach to cytoskeletal fibres and help define and maintain the shape of the cell. Extracellular Matrix: In plant and animal tissues the cell membrane interacts with the cell membrane of adjacent cells. Defines and Encloses the Cell: The membrane allows the cell to control the internal pressure and concentrations of intracellular components. - proteoglycan acts as a mechanical shock barrier. 3. Transport in and out of the cell: Cell membranes ("plasma membranes”) allow transport of specific molecules across the cell membrane in either direction, i.e. either into or out of the cell. Transport can be active or passive. - In active transport the molecules are “pumped” across the membrane. They move against a concentration gradient (e.g. from a lower concentration outside the cell to a higher concentration inside the cell). Active transport requires (uses) energy. - In passive transport molecules drift (diffuse) across the membrane by osmosis and they move with the concentration gradient (from a higher concentration to a lower concentration). Passive transport does not use or require energy, as molecules are moving with the concentration gradient. - Membranes are also involved in bulk transport - exocytosis and endocytosis move items in and out of the cell via secretory vesicles. 4. Markers and Signalling
Surface protein markers embedded in the cell membrane identify the cell, enabling nearby cells to communicate. Cell membranes often include receptor proteins for interaction with specific chemicals (e.g., hormones, neurotransmitters). The cell can recognize and process signals from the environment. The surface markers give your proteins a postcode to make sure that cells are transported to the right place. They also help your organs formed. The postcodes are crucial for a cell to know what kind of cell it is and where it should be. 5. Metabolic Activities Enzyme proteins that perform some metabolic activities are in the membrane. Membrane structure in a mammalian cell
there is a lot of material movement in a membrane. the cell builds a big matrix of stuff that is associated with the membrane Cellular membranes are fluid mosaics of lipids and proteins Phospholipids –abundant • Phospholipids are amphipathic molecules - The fluid mosaic model - membrane is fluid with a “mosaic” of proteins embedded in it Amphipathic – having both a hydrophobic and a hydrophilic end, able to interact with both polar and non-polar substances. From the Greek ‘amphi’ (on both sides) and ‘pathikos’ (suffering or remaining passive).
PL (phospholipid) Phospholipids are mobile in the lateral phase, but they flip flop very infrequently. They flip flop once a month and they laterally move 10^7 times per second.
Points to Remember: The cell membrane has multiple functions. • The cell membrane is a phospholipid bilayer. • The lipid bilayer is a fluid mosaic with properties and behaviours that are defined by the chemical properties of the components. • There are proteins in the membrane and many of these are modified with sugars and lipids. - The membrane is semi-permeable. - The cell membrane has multiple functions. - The cell membrane is a phospholipid bilayer. - The lipid bilayer is a fluid mosaic with properties and behaviours that are defined by the chemical properties of the components. - There are proteins in the membrane and many of these are modified with sugars and lipids. - The membrane is semi-permeable.
Summary of the Difference Between Prokaryotic and Eukaryotic Cells: Prokaryotic Cell Small Cells (5um) Always unicellular No nucleus or any membrane bound organelles such as mitochondria DNA is circular without proteins Ribosomes are small No cytoskeleton Cell division is by binary fusion Reproduction is always asexual Huge variety of metabolic pathways
Eukaryotic Cell Larger Cells (> 10um) Often multicellular Always have nucleus and other membrane bound organelles DNA is linear and associated with proteins to form chromatin Ribosomes are large Always has a cytoskeleton Cell division by mitosis or meiosis Reproduction is asexual or sexual Common metabolic pathways
RNA - 4 bases (G, A, U, C) - single stranded molecule - RNA often folds back on itself and that is how the strands are paired (A & U) (G & C) - Viruses have RNA genome - Our genes encode all the proteins necessary to make a human - Our DNA code contains large amounts of “non - coding or ‘junk sequences” —> the sequences that seem to have nothing in it often encodes RNA. This RNA is often used to regulate how the RNA is translated (turned on and turned off) - some organisms have 6 bases in the genetic code. However generally and for humans there are usually 5 bases Chapter 6: A tour of the cell Eukaryotic Cells have internal membranes that compartmentalise their functions Prokaryotic and Eukaryotic cells Prokaryotic: include bacteria and archaea Eukaryotic: include protists, fungi, animals and plants -
they are both bounded by a selective barrier called the plasma membrane they both have cytosol they both have chromosomes which carry genes in the form of DNA all cells have ribosomes which make proteins according to instructions from the genes the surface to volume ratio is an important parameter affecting cell size and shape. plant and animal cells have most of the same organelles: a nucleus, endoplasmic reticulum, Golgi apparatus, and mitochondria.
Differences: - in a eukaryotic cell most of the DNA is located in the nucleus which is bounded by a double membrane. In a prokaryotic cell the DNA is concentrated in a region that is not membrane encloses called the nucleoid. - Eukaryotic cells are often much larger The relationship between the nucleus and ribosomes: Nucleus: surrounded by a nuclear envelope (double membrane) perforated by nuclear pores; nuclear envelope continuous with endoplasmic reticulum (ER). The nucleus function is to house chromosomes which are made of chromatin (DNA and protein), contains the nucleoli, where ribosomal sub units are made, pores regulate the entry and exit of materials. Ribosome: two sub units made of ribosomal RNA, and proteins; can be free in cytosol or bound to ER. There function is protein synthesis.
The key role played by transport vessels in the endo-membrane system
Mitochondria and chloroplasts change energy form one form to another
The cytoskeleton is a network of fibres that organises structure and activities in the cell - the cytoskeleton functions in structural support for the cell and in motility and signal transmission - microtubules shape the cell, guide organelle movement and separate chromosomes in dividing cells. Cilia and flagella are motile appendages containing microtubules. Primary cilia also play sensory and signalling roles. Microfilaments are thin rods that function in muscle contraction, amoeboid movement, cytoplasmic streaming, and support of microvilli. Intermediate filaments support cell shape and fix organelles in place. Extracellular components and connections between cells help coordinate cellular activities - plant cell walls are made of cellulose fibres embedded in other polysaccharides and proteins - animal cells secrete glycoproteins and proteoglycans that form the extracellular matrix which functions in support, adhesion, movement and regulation - cell junction connects neighbouring cells. plants have plasmodia that pass through adjoining cell walls. Animal cells have tight junctions, desmosomes and gap junctions. Lecture 2 BIOM1050 Module 1: Biology and Chemistry of Cells A tour of cells How does information get from the DNA to the rest of the cell? - the DNA sequence encodes genes - genes encode proteins - proteins do work in the cells - too get from gene to protein, the cell produces an intermediate molecule called messenger RNA (mRNA) in a process called transcription - Transcription (TXN) —> process from changing RNA from DNA) - The cell then uses this mRNA to produce a protein in a process called translation (RLN making protein using mRNA template. There are lots of different types of RNA (mRNA,tRNA etc.)
Prokaryotic - naked DNA (packaged differently Less genetic material in a prokaryotic cell Prokaryotic and eukaryotic cells both have nuclei Nuclei acids = DNA and RNA Both prokaryotes and eukaryotes have nuclei acids What is in a prokaryotic cell? - ribosomes (ribosomes generally make protein) they are in the cytoplasm - carbohydrates - generate ATP using the cell membrane as they don't have a mitochondrion. - membranes - has a membrane around the outside - DNA - protein Module 1: Biology and Chemistry of Cells Lecture 3: The membrane
We can think of the cell as a ‘balloon’ of materials surrounded by a selectively permeable, protective membrane – but cell is not just simple balloon-shaped ball passively floating around
the cell is dynamic and the composition of the membrane differs, depending on the cell type. The plasma membrane: Functions of the cell membrane: - Encloses and Protects the Cell Contents. : The membrane forms a barrier between inside and outside of the cell. Different chemical environments can exist on each side of the cell membrane. The cell membranes are selectively permeable. They allow certain molecules through and block the movement of others. The membrane is made of things with a hydrophilic (outer) and hydrophobic (inner membrane) membrane. Note: sugar and proteins do not dissolve across a membrane. Small gases e.g. O2, CO2 dissolve across a membrane. small molecules (that are polar) disuse across a membrane e.g. CH4, small molecules with some polarity eg. ethanol and methanol dissolve across a membrane however not as well as CH4. Water also dissolves across a membrane however it is slow. Proteins, DNA and RNA, ions, protons, Na+, K+, CE-, H+ never diffuse across a membrane. Anything charged will not defuse across a membrane. The fact the membrane is semi permeable is crucial to the functioning. - proteins are used to actively transport (push things against a concentration gradient), send messaged from the inside and outside of the cell, provides structural strength to the membrane, allows passive transport. - this also happens on the membranes in the organelles e.g. the mitochondria membrane and chloroplasts. It is also still a double membrane 2. Provides and Supports Mechanical Structure: Cytoskeleton: Proteins in the cell membrane attach to cytoskeletal fibres and help define and maintain the shape of the cell. Extracellular Matrix: In plant and animal tissues the cell membrane interacts with the cell membrane of adjacent cells. Defines and Encloses the Cell: The membrane allows the cell to control the internal pressure and concentrations of intracellular components. - proteoglycan acts as a mechanical shock barrier. 3. Transport in and out of the cell: Cell membranes ("plasma membranes”) allow transport of specific molecules across the cell membrane in either direction, i.e. either into or out of the cell. Transport can be active or passive. - In active transport the molecules are “pumped” across the membrane. They move against a concentration gradient (e.g. from a lower concentration outside the cell to a higher concentration inside the cell). Active transport requires (uses) energy. - In passive transport molecules drift (diffuse) across the membrane by osmosis and they move with the concentration gradient (from a higher concentration to a lower concentration). Passive transport does not use or require energy, as molecules are moving with the concentration gradient. - Membranes are also involved in bulk transport - exocytosis and endocytosis move items in and out of the cell via secretory vesicles. 4. Markers and Signalling
Surface protein markers embedded in the cell membrane identify the cell, enabling nearby cells to communicate. Cell membranes often include receptor proteins for interaction with specific chemicals (e.g., hormones, neurotransmitters). The cell can recognize and process signals from the environment. The surface markers give your proteins a postcode to make sure that cells are transported to the right place. They also help your organs formed. The postcodes are crucial for a cell to know what kind of cell it is and where it should be. 5. Metabolic Activities Enzyme proteins that perform some metabolic activities are in the membrane. Membrane structure in a mammalian cell
there is a lot of material movement in a membrane. the cell builds a big matrix of stuff that is associated with the membrane Cellular membranes are fluid mosaics of lipids and proteins Phospholipids –abundant • Phospholipids are amphipathic molecules - The fluid mosaic model - membrane is fluid with a “mosaic” of proteins embedded in it Amphipathic – having both a hydrophobic and a hydrophilic end, able to interact with both polar and non-polar substances. From the Greek ‘amphi’ (on both sides) and ‘pathikos’ (suffering or remaining passive).
PL (phospholipid) Phospholipids are mobile in the lateral phase, but they flip flop very infrequently. They flip flop once a month and they laterally move 10^7 times per second.
Points to Remember: The cell membrane has multiple functions. • The cell membrane is a phospholipid bilayer. • The lipid bilayer is a fluid mosaic with properties and behaviours that are defined by the chemical properties of the components. • There are proteins in the membrane and many of these are modified with sugars and lipids. - The membrane is semi-permeable. - The cell membrane has multiple functions. - The cell membrane is a phospholipid bilayer. - The lipid bilayer is a fluid mosaic with properties and behaviours that are defined by the chemical properties of the components. - There are proteins in the membrane and many of these are modified with sugars and lipids. - The membrane is semi-permeable.
Summary of the Difference Between Prokaryotic and Eukaryotic Cells: Prokaryotic Cell Small Cells (5um) Always unicellular No nucleus or any membrane bound organelles such as mitochondria DNA is circular without proteins Ribosomes are small No cytoskeleton Cell division is by binary fusion Reproduction is always asexual Huge variety of metabolic pathways
Eukaryotic Cell Larger Cells (> 10um) Often multicellular Always have nucleus and other membrane bound organelles DNA is linear and associated with proteins to form chromatin Ribosomes are large Always has a cytoskeleton Cell division by mitosis or meiosis Reproduction is asexual or sexual Common metabolic pathways
