Cells, tissues, muscle, bone Flashcards
What does DNA stand for and what is it?
Deoxyribonucleic acid, it is the blueprint for a living thing. It is a molecule making the shape of a long spiralling ladder, found in the nucleus of a cell in the form of chromosomes.
It tells AMINO ACIDS how to form the perfect protein shape.
It is made up of 4 different types of chemicals (NUCLEOTIDES)
A single strand of DNA is millions of letters long, spending most of it’s life coiled up like a noodle inside a cells nucleus.
What is RNA?
These are special chemicals inside the nucleus that make partial copies of the DNA code (TRANSCRIPTION).
They look a lot like DNA but shorter and only 1 side (of the ladder)
Their small shape and size allows them to fit through tiny pores in the nucleus, into the cytoplasm, and into the ribosome.
What are ribosomes?
They are PROTEIN BUILDING MACHINES.
They read the RNA code 3 letters at a time, suck amino acids out of their surroundings, and stick them together according to RNA code. As the chain grows, it bends, folds and sticks to itself to form a perfectly shaped protein.
Every 3 letters of the code tell the ribosome which of the 20 different kinds of amino acids go next.
Eg. CAA = Glutomine
What is the sequence from DNA?
DNA creates RNA which creates PROTEINS which form LIFE
What are nucleotides?
They are the 4 bases found in DNA.
A - Adenine
G - Guanine
T - Thymine
C - Cytosine
They are arranged in a precise order along the DNA molecule. Each base along one strand of DNA pairs with a base on the other strand in a precise way (known as complementary base pairing)
Adenine pairs with Thymine
Cytosine pairs with Guanine
(The exception here is in mRNA as there is no thymine in RNA, so uracil is added instead to pair with adenine)
The bases run down the middle of the helix and are joined via hydrogen bonds
What is transcription?
It is the process of the DNA template being partially copied to form RNA. It occurs in the nucleus and is catalysed via the enzyme polymerase.
Polymerase unravels the double helix to expose the bases so the code can be read, then produces another strand.
It reads one strand of the dna (the template strand) & uses the strand it has produced to complement the base codes with one change - URACIL is paired with ADENINE instead of thymine.
What is translation?
It is the synthesis of the final protein using information carried on mRNA. It occurs in the cytoplasm, but more specifically the ribosomes. It is the process of a nucleotide sequence being ‘read’ by a ribosome which specifies the amino acid sequence of a protein.
The ribosome slides along the mRNA reading the codons & adding the appropriate amino acid to the growing protein molecule. It carries on until it arrives at a stop codon, where it terminates, synthesises & releases the new protein. Some new proteins are used within the cell itself and some are exported.
Name the 3 types of RNA
mRNA - Messenger RNA. Acts as the messenger between DNA & protein production.
tRNA - Transfer RNA. RNA is generally single stranded, but tRNA folds it into a t shape. It’s responsible for bringing amino acids together during translation to form a peptide chain which becomes a protein. It binds to an amino acid and holds it in place on the ribosome until it is incorporated into a protein.
rRNA - Ribosomal RNA . This is the main component of ribosomes. rRNA combines with special proteins to form ribosomes which then read mRNA to form proteins.
Explain what mitosis is
It is a type of cell division done by most of our body cells, and results in 2 new identical cells with the same number of chromosomes as the original cell.
It is responsible for repair of damage and growth (nails, height etc)
Does NOT create egg or sperm cells.
Where are chromosomes found and how many are they? What are they made out of?
They are found in the nucclei, and there are 46 of them. They are made of DNA and protein.
Summarise the process of mitosis
The initial phase (interphase) is G1 (The cell grows in size and volume), S (Chromosomes replicate making 2 identical copies of DNA. There are now 92 chromatids, but still 46 chromosomes - there is now enough DNA for 2 cells, G2 (further growth and prep for cell division)
Prophase - The replicated chromatin becomes tightly coiled, making it more visable under a microscope. The 46 chromatids pair with the identical chromatid it replicated during interphase, attaching via the centromere creating a double unit chromosome. The mitotic apparatus appears. The centrioles move to opposite ends of the cell and the nuclear envelope dissapears.
Metaphase - The chromatids align in the centre of the spindle and are attached via their centromeres.
Anaphase - The sister chromatids separate along with their centromeres and move to either side of the spindle. The microtubles that form the spindle shorten.
Telophase - The chromosomes are now at 2 opposite ends. The mitotic spindle dissapears and the nuclear envelope develops around each bundle of chromosomes. The chromosomes uncoil, and then cytokinesis occurs. The cytosol, intracellular organelles and plasma membrane split forming 2 identical daughter cells.
Where would you find smooth muscle?
In all the organ systems eg. GI tract, blood vessels
What is an example of a hinge joint and whats its range of motion?
Elbow. There is flexion and extension of the forearm, uni axial movement.
What is an example of a condyloid joint and whats its range of motion?
The wrist. There is flexion, extension, abduction, adduction and circumduction. Bi-axial movement.
What is an example of a ball and socket joint?
The shoulder. Wide range of movement.
What is an example of a saddle joint and what range of motion does it have?
The thumb joint, Bi-axial movement
What are types of synovial joints?
Planar joints
Hinge joints
Pivot joints
Condyloid joints
Saddle joints
Ball & socket joints
What specialised tissue is found on the end of long bones?
Articular Cartilage.
Describe an endocrine gland.
An organ that makes hormones that are released directly into the blood and travel to tissues and organs all over the body. Endocrine glands help control many body functions, including growth and development, metabolism, and fertility. Some examples of endocrine glands are the pituitary, thyroid, and adrenal glands.
What is a dermatome?
They are areas of skin on your body that rely on specific nerve connections on your spine
What is an example of a pivot joint, and what range of motion does it have?
In the neck that allows your head to rotate. It has rotational movement.
What are the islets of Langerhans?
A pancreatic cell that produces hormones (e.g., insulin and glucagon) that are secreted into the bloodstream.
What is the blood brain barrier?
It is a highly selective semipermeable membrane barrier that separates the circulating blood from the brain’s extracellular fluid in the central nervous system (CNS). It selectively allows essential nutrients, oxygen, and certain molecules to enter the brain while preventing the entry of potentially harmful substances, pathogens, and toxins.
What are the 2 types of scwann cells?
Myelinating cells, and nonmyelinating cells.
What are plexuses?
They are networks of interwoven nerve fibers from different spinal nerves.
Examples include the Cervical plexus - provides nerve connections to the head, neck and shoulder
Brachial plexus - located in the neck and shoulders which distributes nerves throughout the chest, shoulders and arms
Lumbar plexus - distributes nerves to back, abdomen, groin, knees, thighs and calves
Sacral plexus - nerves to the pelvis, buttocks, genitals, thighs, calves, feet
What is meiosis?
It’s a process which occurs in the ovaries and testes, producing gametes with half the number of chromosomes (haploid = 23 chromosomes, diploid = two haploids joined).
What is selective permeability?
It is the characteristic which enables the plasma membrane to be selective with which substances enter or leave the cell, therefor regulating the internal composition of the cell.
What is diffusion?
It’s where particles move from a higher concentration to a lower concentration, down a concentration gradient.
What factors effect diffusion?
Temperature, molecular size, speed
What is diffusion through a lipid bilayer?
Non polar hydrophobic molecules such as oxygen, carbon dioxide, carbon dioxide, fatty acids and fat soluble vitamins diffuse freely through a plasma membrane.
Explain diffusion through ion channels
Ion channels are transmembrane proteins that allow small ions to pass through. eg. potassium (K+) and sodium (Na+). These molecules are too hydrophilic to pass through a phospholipid bilayer without a channel. As there are fewer channels in a membrane the process is slightly slower.
Channels can be gated or plugged as the protein changes shape to allow more of fewer ions into or out of a cell.
Ions diffuse down an electrochemical gradient.
What is osmosis?
The passive movement of water from a high concentration to a low concentration.
What is osmotic pressure?
The pressure that develops when two solutions of different concentrations are separated by a semi-permeable membrane, and water molecules move through the membrane to equalize the concentration of solutes on both sides. It is a measure of the force required to stop this flow of water.
The greater the difference in solute concentration between the two solutions, the higher the osmotic pressure. It’s like the “push” that water exerts on the side with higher solute concentration, trying to dilute the more concentrated solution and achieve equilibrium.
What is the function of a ribosome in a cell?
Protein synthesis
What are the three functions of endoplasmic reticulum (rough and smooth)?
Synthesis of fatty acids and steroids
Synthesis of glycoproteins and phospholipids
Intracellular storage of calcium
What is the function of a mitochondrion?
Aerobic cellular respiration and the production of ATP
How many chromosomes does a haploid cell have?
23
What is an example of ciliated simple columnar epithelium?
Uterine tubes
What does an endocrine gland drain into?
Directly into the blood
Name some examples of a serous membrane
Pleura, Peritoneum, Pericardium
What is serous membrane?
The outer lining of organs and body cavities of the abdomen and chest, including the stomach - made of smooth muscle. Secretes serous fluid to allow lubricated sliding movements between opposing surfaces.
What is hemopoiesis?
The production of blood cells
Which part of the long bone contains yellow bone marrow in adults?
Diaphysis (the shaft of central part of a long bone)
What is red bone marrow?
Red bone marrow contains blood stem cells that can become red blood cells, white blood cells, or platelets.
What is yellow bone marrow?
Yellow bone marrow is made mostly of fat and contains stem cells that can become cartilage, fat, or bone cells.
What movement does the levator palebrae superioris muscle create?
Raises the eyelid
What is ossification?
Bone formation
Which proteins are involved in muscle contraction?
Actin, Myosin and Troponin
What do fibroblasts do?
Manufacture collagen and elastin fibres - contributing to the formation of connective tissue.
What three things effect bone growth?
Minerals, hormones and vitamins
What is facilitated diffusion?
It’s the process by which solutes that are two polar or too highly charges to pass through passively, bind to a specific transporter on one side of the membrane and are released on the other side (hitching a lift)
Still a passive process, determined by a concentration gradient.
What is active transport?
It is where transporter proteins (PUMPS) move solutes across a membrane against the concentration gradient and ENERGY (ATP) is required.
Ions that are moved in this way are Na+, K+, amino acids
How does a sodium/potassium pump work and which cells have it?
All cells possess this pump.
Sodium and potassium diffuse down their concentration gradient which results in higher potassium levels on the outside and higher sodium levels on the inside. The pump forces the ions to move from an area of low concentration to an area of high concentration using ATP. It moves soidum ions out of the cell, and potassium ions into the cell to enable to keep the unequal concentrations on either side of the plasma membrane.
Nerve impulses use this electrical gradient.
Transport in vesicles
This is an active process as it requires ATP. Substances are either transported into or out of a cell in a vesicle.
What is phagocytosis?
It translates to ‘cell eating’. It brings in larger particles into a cell such as cell fragments, foreign material and microbes, into a vacuole and is processed in the same way as pinocytosis.
What is pinocytosis?
It translates to ‘cell drinking’. the cell membrane wraps around liquid and larger particles that are outside of the cell, and brings them inside the cell. The membrane breaks off and it becomes a vacuole. Lysosome then binds to the vacuole membrane and releases enzymes to digest the contents, then the waste materials are released back through the membrane in a phase known as exocytosis.
What are the functions of the plasma membrane?
Protecting the contents of the cell
Communicating with other cells
Regulating the flow of materials in and out of the cell
Maintains the appropriate environment within the cell
What is the lipid bilayer?
The lipid bilayer is a type of membrane that separates the cell from the environment and is made of two layers of phospholipids. Also known as the phospholipid bilayer, the cell membrane surrounds the cell and forms a flexible barrier that allows the cell to be separate from the extracellular space.
It is composed of two back to back layers of lipids:
Phospholipids
Cholesterol
Glycolipids
This layer occurs because the lipids are amphipathic (polar and non polar regions). The fatty acid tails (non-polar areas) are in the centre of the bilayer, away from the water in the cytosol and extracellular fluid.
What are membrane proteins and whats their function?
They provide channels for non-lipid soluble substances and electrolytes as they pass all the way through the membrane. They also act as receptors to hormones and c hemical messengers. Some are enzymes.
Some have branches that carbohydrate molecules attach to outside of the cell, giving the cell it’s immunological identity.
What is the cytoplasm?
The cells contents (including the cytosol and organelles, it EXCLUDES the nucleus).
It serves as a medium for important reactions and molecule transport.
What is cytosol?
The watery fluid inside a cell which suspends organelles.
It gives the cell its shape and structure, and is resposible for metabolic reactions eg. glycolosis
What are organelles?
They are the ‘small organs’ inside the cell.
Includes the nucleus, mitochondria, ribosomes, endoplasmic reticulum, golgi apparatus, lysosomes and cytoskeleton.
They are enclosed within their own membrane in the cytosol.
They all have individualised and highly specialised functions.
What is the cytoskeleton
A network of tiny protein fibers.
It’s an internal support system for the cell.
Centrosome
This is made up of a pair of centrioles (small clusters of microtubules). Plays an important part in cell division.
Cilia and flagella
Cilia is microscopic hair like projections containing microtubules that lie along the borders of some cells. They beat in unison to move substances along the surface.
Flagella are single, long, whip like projections containing microtubules which form the tails of spermatozoa.
Golgi complex
Present in all cells but larger in ones that synthesise and export proteins. Made of stacks of closely folded flattened membranous sacs.
Proteins move from the endoplasmic reticulum to the golgi complex where they are packaged into membrane bound vesicles. The vesicles are stored, and when needed get expelled using exocytosis.
Lysosome
Small membranous vesicles pinched off from the golgi complex. They contain enzymes involved in breaking down fragments of organelles and large molecules inside the cell into smaller particles that can then be recycled or exported.
