Topic 2 - Cells & Cancers Flashcards
What 3 things do all cells have in common?
A cell membrane
Cytoplasm
DNA
What does the nucleus of the cell contain?
DNA
What are the two categories of cells?
Prokaryotic
Eukaryotic
What is a cell?
The smallest structural and functional unit of an organism
What are all cells surrounded by?
A plasma membrane
What are the three main ways cells can be connected?
Tight junctions
Anchoring junctions
Gap junctions
What are the features of tight junctions?
They form fluid-tight seals which act as a barrier to fluid loss
They have limited permeability
They prevent molecules from passing through the intracellular space
What is special about gap junctions?
They allow ions and small molecules to pass from cell to cell, to enable intercellular communication
What is the cell cycle?
The cycle of events in eukaryotic cells from one cell division to the next
What are the phases of the cell cycle?
Interphase
Mitosis
Cell division
What can happen if a cell can no longer control mitosis normally?
Tumours may form
What is a tissue?
A group of cells which all perform the same function
What are the four types of bodily tissue?
Epithelium
Connective tissue
Muscle tissue
Nervous tissue
What types of cells are there?
Epithelial Support (eg cartilage, bone) Adipose Contractile (smooth muscle, skeletal muscle) Nerve Gametes Blood Immune system cells Hormone-producing cells
What does the morphology (structure, appearance) of a particular cell tell us?
Its specific function
What are stem cells?
Cells which are able to divide, differentiate and replace specialised cells which are damaged/old
What are the two types of stem cell?
Adult
Embryonic
How are adult stem cells described and what does that definition mean?
As being multipotent, which means they can generate many tissue-specific cell types
How are embryonic stem cells described and what does that definition mean?
Pluripotent, which means they can generate cells of any type in the body
What is the difference between endothelial and epithelial cells?
Epithelial cells line both internal and external surfaces but endothelial cells line internal surfaces of components of the circulatory system
What are endothelial cells?
Cells which line the interior surface of blood and lymphatic vessels
What are epithelial cells and where are they found?
A type of cell which lines every surface of the body
Found on skin, blood vessels, urinary tract, organs
What is an allele?
The dominant form of a given gene
What is a genotype?
Genes which are responsible for a particular trait (eg eye colour)
What is a phenotype?
The physical expression of the genotype (eg blue eyes)
What is a karyotype?
An individual’s collection of chromosomes
What does autosomal mean?
A non sex-related chromosome
What is a nucleotide?
A building block of RNA/DNA
What are the components of a nucleotide?
Phosphate
Sugar (ribose/deoxyribose)
A base
What are the bases?
Adenine
Cystine
Guanine
Thymine (Uracil instead of thymine in RNA)
Which base is different in RNA?
Uracil replaces Thymine
What are amino acids?
Organic compounds which combine to form proteins and are vital for certain functions (eg protein synthesis, tissue repair)
Why are amino acids vital?
They are key to certain physiological functions such as protein synthesis and tissue repair
What is transcription?
The process which makes an RNA copy of a gene sequence
What is translation?
The process of creating proteins from an mRNA template
What is tRNA?
Temporary carriers of amino acids
What is a ribosome?
An organelle which is involved in protein synthesis
Where are ribosomes found?
Freely floating in cytoplasm, or attached to rough endoplasmic reticulum
What are the two main stages of cell division?
Interphase
Mitotic phase
What does eukaryotic mean?
That the cell has a nucleus and membrane enclosed organelles
What is cellular respiration?
The process by which ATP is made
What is transcription and translation?
Transcription is the production of mRNA molecules from the DNA template
Translation is the production of encoded protein from the mRNA
What is a macromolecule? Give an example of one
A molecule containing a large number of atom
Proteins, nucleic acids, synthetic polymers
What determines the folding and shape of a protein?
It’s amino acid sequence
What is the difference between prokaryotic and eukaryotic cells?
Eukaryotic cells contain a nucleus and a range of organelles
Prokaryotic cells only have ribosomes
A plasma membrane surrounds which type/s of cells?
All cells
Are human cells prokaryotic or eukaryotic?
Eukaryotic
What can happen if a cell can no longer control mitosis normally?
Tumours can form
What are ribosomes?
What do they do?
Organelles found in the cytosol
Manufacture proteins
What is an organelle?
Part of the cell which performs a specific function (effectively a cell organ)
What is the nucleus?
The structure where ribosomes are made
What is the Golgi Apparatus?
What does it do?
An organelle which processes and packages proteins and lipid molecules, especially proteins destined to be exported from the cell
It also builds lysosomes (cell digestion machines)
What are vesicles?
Membranous sacs which are usually involved with the transport and secretion of molecules
What are lysosomes?
What do they do?
Specialised vesicles containing enzymes
Their purpose is to digest things
What are mitochondria?
What do they do?
The powerhouse of the cell
They generate most of the chemical energy needed to power the cell’s biochemical reactions
What is the endoplasmic reticulum?
What does it do?
A network of membranes within the cytoplasm of the cell
SER acts as a storage organelle, important in the creation and storage of lipids and steroids
RER is important in the synthesis and packaging of proteins
Why is the rough endoplasmic reticulum (RER) rough?
Because it is studded with ribosomes
What is the rough endoplasmic reticulum’s function?
It plays a central role in the synthesis of proteins
What is the smooth endoplasmic reticulum’s function?
It is involved in the synthesis and storage of lipids
Where are ribosomes made?
In the nucleus
What is the lipid bilayer?
A membrane composed of phospholipid molecules
How is the lipid bilayer composed?
Two layers of phsopholipid molecules; the tails all point inwards and the heads outwards
Why do phospholipid heads point outwards?
They are hydrophilic
Why do phospholipid tails point inwards?
They are hydrophobic
What is an ion channel?
A specialised protein in the plasma membrane which provides a way for charged ions to cross it
What is the purpose of the plasma membrane?
To maintain the integrity of the cell
It also keeps the cytosol (internal fluid) and organelles (suspended objects) separate from the extracellular environment
What determines the fluidity of the plasma membrane?
The composition of lipids and how much cholesterol is present
What determines the permeability of the plasma membrane?
The types of proteins present
What happens in the G_0 phase of the cell cycle?
The cell is quiet at this point
What happens in the G_1 phase of the cell cycle?
The cell synthesises mRNA and proteins in preparation for mitosis
What happens in the S phase of the cell cycle?
DNA is replicated and two complete copies are produced
What happens in the G_2 phase of the cell cycle?
The new cell is checked to ensure it is not defective
Organelles multiply
Extra protein is synthesised
Materials (eg lipids) for the membrane may be produced
What happens in the M phase of the cell cycle?
The cell divides into two daughter cells
What does amphipathic mean?
To have dual polarity
How do CO2 and small molecules cross the plasma membrane?
By diffusion
How do ions or larger molecules cross the plasma membrane?
Proteins facilitate them crossing as they are too large for diffusion
What are the two main qualities of the plasma membrane?
Fluidity
Permeability
How does primary active transport work?
Chemical energy (eg ATP) is used to move molecules over a membrane against their gradient
What is secondary transport?
Transport via the concentration gradient that is created by primary active transport
What is meant by the term “simple diffusion”?
Passive diffusion of ions/molecules via specific proteins (channels, carriers, transporters)
What do symporters do?
Transport molecules/ions across the phospholipid membrane in the same direction as the concentration gradient
What do antiporters do?
Transport molecules/ions across the phospholipid membrane in the opposite direction to the concentration gradient
What is cytoplasm composed of?
Cytosol (fluid within the cell)
Cell organelles
What is exocytosis?
The process of moving materials from within a cell to the exterior of a cell
What is endocytosis?
The process of moving materials from outside a cell to within it
Aside from proteins, what other substances are exported out of a cell by exocytosis?
Waste products
What is meant by the term “facilitated diffusion”?
The passive transport of molecules or ions across the plasma membrane, via specific proteins (channels, carriers, receptors)
What are the two reasons solutes are able to diffuse across the plasma membrane?
A concentration gradient exists across the membrane
The solute can pass freely across the membrane
What is a concentration gradient?
A process which is used for moving particles from an area of higher concentration in a solution to an area of lower concentration
Why are concentration gradients important?
They allow for the movement of solutes and gases by diffusion
Is ATP required in the process of simple diffusion?
No
What is ion channel diffusion?
Transport across cell membranes which occurs due to ion channels within the membrane
What is carrier-mediated diffusion?
Diffusion across the plasma membrane which is facilitated by carrier proteins such as glucose
Roughly how much of a cell’s energy is spent in maintaining a concentration gradient across the plasma membrane?
About 45%
What is the sodium-potassium pump?
A specialised type of transport protein which is found in the cell membrane
What are the ratios of sodium and potassium which are transported by the sodium-potassium pump?
3 sodium ions out for every 2 potassium ions brought in
What is the purpose of the sodium-potassium pump?
It underlies most of our cellular processes
What powers the sodium-potassium pump?
ATP
How does the sodium-potassium pump work?
Sodium ions bind to the pump
A phosphate group from ATP attaches to it, causing it to change shape
The pump then releases 3 sodium ions
It binds to 2 potassium ions
The phosphate group detaches, causing the pump to release the 2 potassium ions into the cytoplasm
What is the alternative name for the sodium-potassium pump?
Sodium-potassium ATPase
The sodium-potassium pump is an example of which type of cellular transport?
Primary active transport
How do carrier mediated proteins work?
They change shape to faciliate diffusion of solutes across the cell membrane
What is ATP composed of?
Ribose (a pentose sugar)
Adenine (nitrogenous base)
Three phosphate groups
What are the products of ATP being broken down?
ADP (adenosine diphosphate)
A single phosphate group
What is phosphorylation?
The process of adding a single phosphate group to an existing molecule in order to prepare it to change or do work (eg the addition of phosphate to ADP in order to form ATP)
Where in the body might you find epithelial cells?
The lining of the digestive tract and blood vessels
The outer layer of skin
Give some examples of places in the body you might find support cells
Fibrous support tissue
Cartilage
Bone
Where in the body might you find adipose cells?
Under the skin
Around organs
Where in the body might you find contractile (muscle) cells?
Skeletal muscle
Heart muscle
Smooth muscle
Where in the body might you find neurons?
Brain
Spinal cords
Where in the body might you find gametes?
Eggs/sperm
Where in the body might you find blood cells?
Circulating red and white cells
Where in the body might you find immune system cells?
Lympoid tissues (lymph nodes, spleen)
Where in the body might you find hormone-producing cells?
Thyroid/adrenal glands
Pancreas
What are the properties of (cellular) tight junctions?
They form a fluid-tight seal, enabling entire sheets of cells to join together
This acts as a barrier to fluid loss
What are the properties of (cellular) anchoring junctions?
They join tissues subjected to stretching or friction
What are the properties of (cellular) gap junctions?
They bring cell membranes close together, meaning small molecules can pass directly from the cytosol of one cell into the cytosol of another cell
What must first happen to the genetic material contained in a cell before it can divide and form two new cells?
The chromosomes must be duplicated so that each new cell contains a full copy of the genome
What is meant by the term “somatic cell division”?
The type of cell division where daughter cells are identical to the parent cell
What is cytokinesis?
The part of the cell division process where the cytoplasm of a single eukaryotic cell divides and forms two daughter cells
In the human cell cycle, at what stage does cytokinesis (cytoplasmic division) occur?
During anaphase and continues through telophase
What is prophase?
What occurs at this stage of the cell cycle?
The first stage of cellular replication
The parent cell chromosomes condense, the nucleolus disappears, the mitotic spindle starts to form
What is metaphase?
What occurs at this stage of the cell cycle?
The second stage of cell division
The chromosomes align with the middle of the cell, ready to divide
What are the two main phases of the cell cycle?
Interphase
Mitotic phase
What events occur during the S phase of cellular reproduction?
The DNA within the cell is replicated, producing two complete copies of the cell
What are the four main phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
For someone aged over 50, roughly how long does it take for the epidermis to renew itself?
Up to 84 days
What structures are you likely to find in the dermis layer of skin?
Sebaceous glands Hair erector muscles Sweat glands Lymphatic vessels Hair follicle
How are cells in different layers of skin distinguished from one another?
By the level of their content of keratin (increases toward the surface)
What are the two types of stem cells?
Adult
Embryonic
Are adult stem cells multipotent or pluripotent?
Multipotent
What does multipotent mean (in reference to stem cells)?
Stem cells which are able to generate multiple, tissue-specific cell types
What does pluripotent mean (in reference to stem cells)?
Stem cells which are not limited to generating cell types of a particular tissue, but which can generate cells of any type within the body
What are induced pluripotent stem cells?
Stem cells which are generated in research laboratories using cells harvested from adults and that have been “reprogrammed” to become pluripotent
What is the epidermis?
The surface layer of the skin
