MCD - Cells & Organelles

Question 1

Heterochromatin

Answer 1

Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.

Question 2

Euchromatin

Answer 2

Loosely packed DNA which allows transcription to take place.

Question 3

Adhesion Plaques

Answer 3

Actin filaments in the cell surface that attach the cell to surrounding cells, to form tissue, and to the extra cellular matrix.

Question 4

Nucleus

Answer 4

Contains DNA in the form of chromatin

Question 5

Nucleolus

Answer 5

The site of production of ribosomes

Question 6

Nuclear pores

Answer 6

Holes in the nuclear envelope that control the passage of molecules - for example mRNA

Question 7

Rough Endoplasmic Reticulum

Answer 7

The site of protein synthesis - mainly for use outside the cell

Question 8

Ribosome

Answer 8

The site of protein synthesis - mainly for use within the cell

Question 9

Smooth Endoplasmic Reticulum

Answer 9

Production of lipids

Question 10

Golgi Apparatus

Answer 10

Modifies and packages proteins

Question 11

Mitochondria

Answer 11

Produces ATP for reactions that require energy

Question 12

Cell

Answer 12

The basic unit of life

Question 13

Tissue

Answer 13

A group of cells working together to perform a particular function

Question 14

Organ

Answer 14

A group of tissues working together to perform a particular function

Question 15

Organ System

Answer 15

A group of organs that work together to perform a particular function.

Question 16

Polarity

Answer 16

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.

Question 17

Organism

Answer 17

A living thing that can carry out the 7 life prossesses (MRS GREN)

Question 18

Actin

Answer 18

A component of the cytoskeleton which allows cell movement in cytokinesis, and lines the cell membrane to hold proteins in place.

Question 19

Microtubules

Answer 19

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.

Question 20

Intermediate Filaments

Answer 20

A component of the cytoskeleton which acts as scaffolding, holding the organelles in the correct arrangement.

Question 21

Specialisation

Answer 21

Specific genes within cells are switched on and off, resulting in production of particular proteins that allow th cell to perform its function.

Question 22

Secretory Granules

Answer 22

The membrane bound organelle where molecules are stored before being secreted from the cell by exocytosis.

Question 23

Lysosomes

Answer 23

Membrane bound organelles containing hydrolytic enzymes, used to break down old organelles and in phagocytosis.

Question 24

Liposomes

Answer 24

Membrane bound organelles formed from th lipid bilayer.

Question 25

Cilia

Answer 25

Hair like projections that beat to move fluid over the epithelial tissue. Made of microtubules.

Question 26

Nucleolus

Answer 26

Produces ribosomes

Question 27

What are the main functions of the blood?

Answer 27

Transport, heat distribution, immunity, haemostasis and homeostasis

Question 28

Describe the erythrocytes life cycle

Answer 28

- 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

Question 29

What are immature erythrocytes?

Answer 29

Reticulocytes - contain ribosomes.

Question 30

What is the oxidised form of haemoglobin?

Answer 30

Methaemoglobin

Question 31

How does oxygen bind to haemoglobin?

Answer 31

Cooperatively, where the shape changes as every oxygen is added making it easier for the next one to bind.

Question 32

What is haemocrit?

Answer 32

Packed cell volume

Question 33

What is anaemia?

Answer 33

Low blood haemoglobin concentration

Question 34

What is microcytic anemia?

Answer 34

Small MCV - lack of iron due to menstruation, parasitic infections or GIT lesion

Question 35

What is normocytic anemia?

Answer 35

Normal MCV, due to acute blood loss

Question 36

What is macrocytic anemia?

Answer 36

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.

Question 37

What are the types of leukocytes?

Answer 37

- Polymorphonuclear granulocytes (multilobed nuclei, many granules) - Lymphocytes - Monocytes

Question 38

What are the types of polymorphonuclear granulocytes?

Answer 38

Neutrophils which are phagocytic, eosinophils which are involved in allergies, and basophils which produce histamine.

Question 39

What are the characteristics of polymorphonuclear granulocytes?

Answer 39

- 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)

Question 40

What are B lymphocytes?

Answer 40

White blood cells that mature in the bone marrow, involved in humoural immunity. They produce antibodies used in precipitation, opsonisation, neutralisation and agglutination.

Question 41

What are T lymphocytes?

Answer 41

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)

Question 42

What are monocytes?

Answer 42

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.

Question 43

What is the normal leukocyte count?

Answer 43

Many neutrophils, then lymphocytes, then monocytes, then eosinophils, then basophils.

Question 44

What is the function of platelets?

Answer 44

- 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.

Question 45

What is the function of plasma?

Answer 45

Fluid component of blood, carrier of plasma proteins.

Question 46

What is serum?

Answer 46

Plasma with proteins removed due to clotting

Question 47

What are the types of plasma proteins? What is their function?

Answer 47

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)

Question 48

What is the basic structure of haemoglobin?

Answer 48

4 subunits, each with a haem group (ferrous iron).

Question 49

What is the structure of erythrocytes?

Answer 49

Biconcave shape, no nucleus, molecules on surface confer blood group. Carries oxygen and carbon dioxide around the blood.

Question 50

What is passive immunity?

Answer 50

Short term immunity using antibodies produced outside the body, such as from a mother or an injection.