MCD - Cells & Organelles Flashcards
Heterochromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.
Euchromatin
Loosely packed DNA which allows transcription to take place.
Adhesion Plaques
Actin filaments in the cell surface that attach the cell to surrounding cells, to form tissue, and to the extra cellular matrix.
Nucleus
Contains DNA in the form of chromatin
Nucleolus
The site of production of ribosomes
Nuclear pores
Holes in the nuclear envelope that control the passage of molecules - for example mRNA
Rough Endoplasmic Reticulum
The site of protein synthesis - mainly for use outside the cell
Ribosome
The site of protein synthesis - mainly for use within the cell
Smooth Endoplasmic Reticulum
Production of lipids
Golgi Apparatus
Modifies and packages proteins
Mitochondria
Produces ATP for reactions that require energy
Cell
The basic unit of life
Tissue
A group of cells working together to perform a particular function
Organ
A group of tissues working together to perform a particular function
Organ System
A group of organs that work together to perform a particular function.
Polarity
The distribution of organelles within a cell is uneven, therefore it is asymmetrical. A structure with inherent asymmetry so that one end can be distinguished from the other.
Organism
A living thing that can carry out the 7 life prossesses (MRS GREN)
Actin
A component of the cytoskeleton which allows cell movement in cytokinesis, and lines the cell membrane to hold proteins in place.
Microtubules
A component of the cytoskeleton high forms centrioles, cilia, and flagellum, as well as forming pathways for motor proteins to transport substances around the cell.
Intermediate Filaments
A component of the cytoskeleton which acts as scaffolding, holding the organelles in the correct arrangement.
Specialisation
Specific genes within cells are switched on and off, resulting in production of particular proteins that allow th cell to perform its function.
Secretory Granules
The membrane bound organelle where molecules are stored before being secreted from the cell by exocytosis.
Lysosomes
Membrane bound organelles containing hydrolytic enzymes, used to break down old organelles and in phagocytosis.
Liposomes
Membrane bound organelles formed from th lipid bilayer.
Cilia
Hair like projections that beat to move fluid over the epithelial tissue. Made of microtubules.
Nucleolus
Produces ribosomes
What are the main functions of the blood?
Transport, heat distribution, immunity, haemostasis and homeostasis
Describe the erythrocytes life cycle
- Low O2 detected by the kidney
- Erythropoietin produced by the bone marrow stem cells¬ which stimulates erythropoiesis.
- Erythrocytes are made, and last 120 days
- Removed by the reticulo-endothelial system in the spleen
What are immature erythrocytes?
Reticulocytes - contain ribosomes.
What is the oxidised form of haemoglobin?
Methaemoglobin
How does oxygen bind to haemoglobin?
Cooperatively, where the shape changes as every oxygen is added making it easier for the next one to bind.
What is haemocrit?
Packed cell volume
What is anaemia?
Low blood haemoglobin concentration
What is microcytic anemia?
Small MCV - lack of iron due to menstruation, parasitic infections or GIT lesion
What is normocytic anemia?
Normal MCV, due to acute blood loss
What is macrocytic anemia?
Large MCV, lack of folic acid/vitamin B12 in pregnancy results in cells not dividing correctly. Fewer but larger blood cells. Also caused by an autoimmune disease/in vegans or vegetarians.
What are the types of leukocytes?
- Polymorphonuclear granulocytes (multilobed nuclei, many granules)
- Lymphocytes
- Monocytes
What are the types of polymorphonuclear granulocytes?
Neutrophils which are phagocytic, eosinophils which are involved in allergies, and basophils which produce histamine.
What are the characteristics of polymorphonuclear granulocytes?
- Segmented nucleus
- Abundant cytoplasmic granules
- First on scene
- Adhere to blood vessels and migrate to tissue
- Engulf and digest microorganisms
- Release inflammatory mediators (toxic oxygen products, digestive enzymes, chemotaxins, vasodilators)
What are B lymphocytes?
White blood cells that mature in the bone marrow, involved in humoural immunity. They produce antibodies used in precipitation, opsonisation, neutralisation and agglutination.
What are T lymphocytes?
Thymus dependent (derived in bone marrow, aquire surface receptors in the thymus). They are involved in cellular immunity (chemotaxis attracts macrophages, lymphotoxin kills cells, interferon kills viruses)
What are monocytes?
Large blood cells, with a horse shoe nucleus. They appear after granulocytes, and become macrophages in the tissue. Engulf microorganisms and stimulate angiogenesis (vessel growth/repair). Also secrete inflammatory mediators.
What is the normal leukocyte count?
Many neutrophils, then lymphocytes, then monocytes, then eosinophils, then basophils.
What is the function of platelets?
- Derive from megakaryocytes, have no nucleus but many organelles.
- They have receptors for platelet activators (eg. Collagen or thrombin).
- In Haemostasis, they bind to exposed collagen and release of granules stimulates aggregation.
- Involved in clot formation.
What is the function of plasma?
Fluid component of blood, carrier of plasma proteins.
What is serum?
Plasma with proteins removed due to clotting
What are the types of plasma proteins? What is their function?
Plasma proteins exert osmotic pressure to maintain blood volume. They include albumins & globulins (carrier molecules such as hormones/bile salts) and fibrinogen (clotting/platelet aggregation)
What is the basic structure of haemoglobin?
4 subunits, each with a haem group (ferrous iron).
What is the structure of erythrocytes?
Biconcave shape, no nucleus, molecules on surface confer blood group. Carries oxygen and carbon dioxide around the blood.
What is passive immunity?
Short term immunity using antibodies produced outside the body, such as from a mother or an injection.
