CELLS Flashcards

Question

Prokaryotic: Mesosomes

Answer 1

Infoldings of the inner membrane which contain enzymes required for respiration

Answer 2

Division of a cell that results in each of the daughter cells having an exact copy of the DNA of the parent cell. Doesn't give rise to genetic variation

Answer 3

Stage between one cell division and the next 90% of the time cells are in interphase DNA is spread out as chromatin and chromosomes aren't visible

Answer 4

Chromosomes condense and become visible Centrioles move to two poles of the cell from which spindle fibres develop Nucleolus disappears and nuclear envelope breaks down so the chromosomes are free in the cytoplasm of the cell

Answer 5

Chromosomes are now seen to be made up of two chromatids which are joined by the centrometre Chromosomes line up on the equator Spindle fully forms

Answer 6

Centrometres split into trow and chromatids are pulled apart to opposite ends of the cell Energy for this process is provided by mitochondria which gather around the spindle fibre cells

Answer 7

Nuclear membrane forms Cytoplasm divides

Answer 8

1. GROWTH = all cells produced are identical so organisms can grow using mitosis. 2. REPRODUCTION = single celled organisms divide by mitosis 3. REPAIR = all cells produced are identical so organisms can replace dead tissues using mitosis.

Answer 9

Used by prokaryotic cells to divide * replication of the circular DNA and of plasmids * division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids.

Answer 10

When some cells don't divide continuously but still undergo a regular cycle of division separated by periods of cell growth it is known as the cell cycle

Answer 11

Interphase Nuclear division Cytokinesis

Answer 12

Occupies most of the cell cycle no division takes place

Answer 13

Nucleus divides into either 2 (mitosis) or 4 (meiosis)

Answer 14

Cytoplasm divides to produce 2 (mitosis) or 4 (meiosis) new cells.

Answer 15

A group of diseases caused by a growth disorder of cells It is the result of damage to the genes that regulate mitosis and the cell cycle. leads to an uncontrolled growth and division of cells and a tumour develops

Answer 16

the rate of mitosis can be controlled by two types of genes. A mutation to one of these results in uncontrolled mitosis which forms tumours.

Answer 17

Involves killing cells by blocking a part of the cell cycle. Drugs to do this prevent the cell cycle by: 1. preventing DNA from replicating 2. inhibiting the metaphase stage of mitosis by interfering with spindle formation PROBLEMS: disrupt cell cycle of normal cells but the drugs are more effective against rapidly dividing cells.

Answer 18

organelle controls what substances enter and leave the cell

Answer 19

PHOSPHOLIPIDS : All membranes are made up of a phospholipid bilayer with the hydrophilic heads pointing outwards and the hydrophobic tails pointing inwards PROTEINS : 2 types of proteins in a membrane 1. Extrinsic - lie on one side of membrane only 2. Intrinsic - span the membrane from one side to the other

Answer 20

-only allow small molecules through (selectively permeable) - Small molecules can diffuse through the phospholipid bilayer - Large molecules can only diffuse if they are lipid soluble

Answer 21

how scientists describe what the cell membrane looks and functions like Fluid : Phospholipid molecule move relative to each other giving the molecule a flexible structure Mosaic : Proteins vary in size Glycoprotein = Branching carbohydrate portion of a protein that acts as a recognition site

Answer 22

Mechanical support to membrane Protein channeled that transport water-soluble ions across the membrane Allow active transport across the membrane via carrier proteins Conjunction with glycolipids as cell receptors for molecules such as hormones

Answer 23

CHOLESTEROL - makes the membrane more rigid and reduces the lateral movement of the phospholipids. It also prevents the leakage of water and dissolved ions from the cell as it is very hydrophobic. PHOSPHOLIPIDS - made up of a phospholipid with carbohydrate attached, extend from the surface of the cell and acts as a cell surface receptors for certain molecules. Also allows cells to adhere to one another to form tissues. GLYCOLIPIDS - carbohydrates that attach to extrinsic proteins and acts as a cell surface receptors and neurotransmitters. They help cells to attach and form tissues

Answer 24

The net movement o particle from a region of relatively high concentration to a region of lower concentration

Answer 25

Temperature : warm molecules have more kinetic energy Size of molecule - small molecules have more kinetic energy Concentration gradient - steeper gradient the faster the diffusion Nature of molecule - lipid soluble gets across membrane faster, non polar diffuse faster than polar Thickness of membrane - thicker membrane, greater diffusion distance Surface area of membrane - greater surface are = faster diffusion Number of specific carrier/channel proteins - more proteins, the faster diffusion will happen

Answer 26

The net movement of particle down a concentration gradient that only happens with the help of carrier or channel proteins

Answer 27

They can be carrier or channel and are: - Intrinsic - Specific to one type of molecule - Have binding sights for that molecule

Answer 28

Form hydrophyllic channels across membranes Transport water soluble ions Can be gated

Answer 29

Molecule attaches to the binding site which causes the protein to change shape Molecule is then deposited on the other side of the membrane No energy is needed and they only transport molecules down a concentration gradient.

Answer 30

They give the cell the ability to control what enters and leaves the cell or the internal organelles

Answer 31

Movement of water from a higher water potential to a lower water potential across a partially permeable membrane

Answer 32

A measure of the pressure created by water molecules Measured in kilopascals Pure water has the highest water potential (0KPa) - All solutions are compared to pure water and so have negative water potentials

Answer 33

HYPOTONIC: - Water potential in surrounding solution: Less negative - Water movement between cell and solution: Moves into cell Effect on cell: Swells and bursts (animal). Plants become turgid ISOTONIC: - Water potential in surrounding solution: Same - Water movement between cell and solution: No movement Effect on cell: No change in animals. Plants = incipient plasmolysis HYPERTONIC: - Water potential in surrounding solution: More negative - Water movement between cell and solution: Moves out of cell Effect on cell: Shrinks in animals. Plants = plasmolysed.

Answer 34

Movement of molecules from a region of their lower concentration to a region of their higher concentration using carrier proteins and energy

Answer 35

- Substances move against their concentration gradient - Require specific carrier proteins which need energy in the form of ATP to change shape and deposit the molecules on the other side of the membrane - ATP is needed to change to the shape of the protein

Answer 36

Because it requires energy - If respiration stops active transport stops so cells only use active transport to move important molecules

Answer 37

1. Na+ ions are actively transported out of the epithelial cells in the ileum by a sodium - potassium pump into the blood this takes place in a specific carrier protein 2. Higher concentration of sodium in the lumen of small intestine than epithelial cells 3. Na+ ions diffuse into the epithelial cells down this concentration gradient and bring amino acids along with them 4. Amino acids then pass into the blood plasma via facilitated diffusion

Answer 38

1. SKIN = tough physical barrier consisting of keratin 2. STOMACH ACID = HCL kills bacteria 3. GUT AND SKIN FLORA = natural bacterial flora competes with pathogens for food and space

Answer 39

= responses is immediate and the the same for all pathogens 1. physical barriers 2. phagocytosis

Answer 40

= response is slower and specific to each pathogen 1. cell mediated response 2. humoral response

Answer 41

Phagocytes (type of white blood cell) - ingest and destroy the pathogen before it can cause harm

Answer 42

1. Chemical products of pathogens act as attractants causing phagocytes to move towards the pathogen 2. Phagocytes have several receptors on their cell-surface membrane that recognise and attach to chemicals on the surface of the pathogen 3. Engulf the pathogen to form a vesicle known as a phagosome 4. Lysosomes move towards the vesicle and fuse with it 5. Enzymes calls lysozomes are present within the lysosome. These enzymes destroy ingested bacteria by hydrolysis of their cell walls 6. The soluble products from the breakdown of the pathogen are absorbed into the cytoplasm of the phagocyte

Answer 43

cells that display foreign antigens on their surface are called antigen-presenting cells - as they present antigens of other cells on their own cell surface membrane

Answer 44

Antigens that are presented on a body cell rather than to antigens within the body fluids - receptors on each T cell respond to a single antigen

Answer 45

1. Pathogens invade body cells or are taken in by phagocytes 2. The phagocyte places antigens from the pathogen on its cell surface membrane 3. Receptors on a specific helper T cell fit exactly onto these antigens 4. This attachment activated the T cell to divide rapidly by mitosis and form a clone of genetically identical cells 5. The cloned T cells: a) develop into memory cells b) stimulate phagocytes to engulf pathogens by phagocytosis c) stimulate B cells to divide and secrete their antibody d) activate cytotoxic T cells

Answer 46

kill abnormal cells and body cells that are infected by pathogen by producing a protein that makes hole in the cell surface membrane ( becomes permeable to everything and so the cell dies)

Answer 47

Involves antibodies - there are many diff types of B cell and each B cell produces a specific antibody that responds to one specific antigen

Answer 48

1. Surface antigens of an invading pathogen are taken up by a B cell 2. The B cell processes the antigens and presents them on its surface 3. Helper t cell (cell mediated activated ones) attach to the processed antigen on the B cell = activates the B cell 4. B cell divides by mitosis to give a clone of plasma cells 5. Cloned plasma cells produce and secrete the specific antibody that exactly fits the antigen on the pathogen surface 6. Antibody attached to antigens on the pathogen and destroys them 7. Some B cells develop into memory cells. Respond to future infections by dividing rapidly and developing into plasma cells that produce antibodies

Answer 49

Plasma cells secrete antibodies into blood plasma - these antibodies lead to the destruction of the antigen. Production of antibodies and memory cells is known as the primary immune response

Answer 50

Memory cells = secondary response - Live longer than plasma cells and don't produce antibodies but circulate in the blood and tissue fluid Divide rapidly into plasma cells and more memory cells when antigen is encountered again ( provides long term immunity)

Answer 51

antibodies are proteins with specific binding sites synthesised by B cells. - binding sites are specific to a complementary antigen and variety of antibodies is possible because they are made of many proteins

Answer 52

-four polypeptide chains = long heavy chains and shorter light chains - specific binding site that fits very precisely onto a specific antigen to form an antigen-antibody complex

Answer 53

binding site is different on different antibodies and this is called the variable region - rest of antibody is the constant region

Answer 54

clumps of bacterial cells are formed making it easier for the phagocytes to locate them as they are less spread out within body - possible due to each antibody having two antigen binding sites - serve as markers that stimulate phagocytes to engulf the bacterial cells to which they are attracted

Answer 55

antibodies which are produced by a single clone of a specific white blood cell. they are specific to one binding site on one protein antigen so they are able to target specific cells

Answer 56

1. monoclonal antibodies are produced that are specific to antigens on cancer cells 2. these antibodies are given to a patient and attach themselves to the receptors on their cancer cells 3. They attach to the surface of their cancer cells and block the chemical signals that stimulate their uncontrolled growth - example is herceptin + since antibodies aren't toxic and are highly specific they lead to fewer side effects than other forms of therapy

Answer 57

Involves attaching a radioactive or cytotoxic drug to the monoclonal antibody - when the antibody attaches to the cancer cells it kills them

Answer 58

important in diagnosis of certain cancer.

Answer 59

produced by the introduction of antibodies into individuals from an outside source - no direct contact with the pathogen is necessary to induce immunity = immunity is acquired immunity - no memory cells as antibodies aren't replaced when broken down = no lasting immunity

Answer 60

produced by stimulating the production of antibodies by the individuals own immune system - direct contact with pathogen is necessary - long lasting and there are two types 1. Natural =individual is infected with a disease under normal factors 2. Artificial = inducing an immune response in an individual (no sypmtoms) = vaccine

Answer 61

1. Economically available in sufficient quantities to immunise most of the vulnerable population 2. Few side effects 3. Means for production, storing and transportation must be available 4. Appropriate means of administration

Answer 62

When a sufficiently large proportion of the population has been vaccinated making it difficult for a pathogen spread within a population

Answer 63

Its impossible for a whole population to be vaccinated e.g. provides protection for babies and the elderly

Answer 64

1. Vaccination facts to induce immunity in certain individuals e.g. people with defective immune systems 2. Pathogen may frequently mutate so its antigen change suddenly. Vaccines become ineffective as the new antigens aren't recognised by the immune system 3.May be loads of variety of a particular pathogen that its impossible to vaccinate against them all e.g. the cold 4. Individuals may have objection to vaccines due to religion, ethical or medical reasons

CELLS Flashcards

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