3.2 Cells

Cell-surface membranes

Regulators movement, growth and balance of endocytosis and exocytosis. Receptor molecules, cholesterol, glycolipids. Lipids give flexibility. Proteins maintain gradients and assist transfer. Hydrophobic head, hydrophilic tail, semi-permeable bilayer.

1 of 58

Nucleus

Controls DNA transcription. Surrounded by nuclear envelope and pores + contains genetic material. Ribosomes produced in the centre and pores allow substances to move between nucleus and cytoplasm.

2 of 58

Nucleolus

Located in centre of a nucleus and comosed of DNA, RNA and proteins. Functions to produce subunits which form ribosomes.

3 of 58

Mitochondria

Site of aerobic respiration where ATP is produced. Found in large numbers in cells that require energy. Powerhouse of the cell. Typically 200 in a cell but can be 1-10,000. Inner membrane that folds to create cristae. Inside has fluid-filled matrix.

4 of 58

Chloroplasts

Site of photosynthesis, surrounded by double membrane. Outer contains porins and inner is impermeable so need trasporters. Thylakpod is s membrane system that carries out PS. Stroma contains important metabolic products like ions and enzymes/

5 of 58

Cytoplasm

Gel which contains all cell organelles. Enclosed by cell membrane.

6 of 58

Golgi apparatus

Processes and packages new lipids and proteins in vesicles. Makes lysosomes. Group of fluid-filled, membrane bound sacks. Receives proteins and lipids from the RER

7 of 58

Lysosomes

Contains digestive enzymes called lysozymes that can digest invading cells or break down worn out components. Type of golgi vesicle. Round organelle with no clear internal structure. Acts as cells waste disposal system.

8 of 58

Centriole

Help a cell to divide in mitosis and meiosis. Found neat the nucleus but can't be seen outside division. Microtubules arranged at right angles. Move to opposite ends during cytokineses.

9 of 58

Ribosomes

The site where proteins are made. Very small molecules made up of two subunits. Either floats free or is attached to the RER. Synthesises proteins from RNA and amino acids

10 of 58

Cytoskeleton

Responsible for cell mobility, movement and division. Consists of microtubules, actin and tubulin

11 of 58

Rough Endoplasmic Reticulum

Folds and processes proteins made at the ribosome. Membranes are covered in ribosomes. System of membranes that encloses a fluid-filled space.

12 of 58

Smooth Endoplasmic Reticulum

Synthesises and processes lipids. Similar structure, no ribosomes. Creating and storing steroids, cholesterol and detoxification

13 of 58

Cell Wall

Supports plant cells and precents them changing shape. Made of cellulose (chitin in fungi)

14 of 58

Vacuole

Helps to maintain pressure inside the cell and keep it rigid. Isolation of unwanted chemical inside the cell. Formed when vesicles from the ER and Golgi apparatus merge. Both detox and lytic role. Membrane bound.

15 of 58

Vesicle

Packages proteins and transport molecules round the cell. Round structures.

16 of 58

Epithelial cells in small intestine

Lots of villi that increase SA, microvilli on surface further increase SA. Lots of mitochondria to provide energy for transport of food into the cell. Ep -> Ep tissue +glandular tissue+muscle tissue=stomach

17 of 58

Erythrocyte (Red blood cells)

Contains Hb which allows binding of oxygen. No nucleus to allow more Hb+02 and cell can fit through capillaries. Flexible and thin membrane. Biconcave shape so furface and curve inwards and increase SA and efficiency of oxygen absorption

18 of 58

Neutrophil

WBC that ingests and absorbs invading MOs. Large amount of lysosomes. Lobed nucleus for better flexibility

19 of 58

Sperm cell

Head contains genetic info, middle mitochondria. Long tail helps movement. Head contains acrosome which releases enzyme to help penetrate egg cell

20 of 58

Root hair cell

Long tail with thin wall gives large SA and aids water transport. Large no of mitochondria provide energy

21 of 58

Palisade Cell

Large amount of chloroplasts and chlorophyll. Long shaped and closely packed make light absoprtion efficient

22 of 58

Guard cell

Regulate transpiration and water loss by opening and closing stomata. Spiral thickening of cellulose means it opens when cells are turgid.

23 of 58

Cilliated epithelium

Cillia produced by cytoplasm wave back and forth to move particles out the respiratory tract. Trap dust and bacteria in the air we breathe and causes sneezing.

24 of 58

Resoultion and Magnification

Resolution is how well a microscope distinguished between close objects. Magnification is how much bigger the image is than the specimen. Image size/actual size.

25 of 58

Artefact

Something on the slide that can be seen but isn't part of the specimen, for example air bubbles or damage on slides.

26 of 58

Strengths and Weaknesses of light microscopes

-Simple and cheap technique -Can view living material as no vaccum is required -Colour images -Low resolving power and magnification and least clear resolution

27 of 58

Strengths and Weaknesses of electron microscopes

-Shorter wavelengths and higher resolving power so better detailed images -Expensive and technical procedure - Only dead and dried specimen can be seen

28 of 58

Interphase

Cell prepares to divide. G1- Cell grows and proteins are made. S- Cell replicates its DNA G2- Proteins needed for division are made and organelles replicate

29 of 58

Prophase

Chromosomes codnense and coil, getting shorter. Centrioles form spindle fibres a they start to move. Nuclear envelope disappears and chromosomes are free

30 of 58

Metaphase

Chromosomes line up along the middle of the cell and becoem attached to the spindle by their centromere

31 of 58

Anaphase

Centromere divides, separating sister chromatids. Spindle fibres contract, pulling chromatids to opposite poles of the spindle. Chromatids become chromosomes

32 of 58

Telophase

Two sets of chromosomes collect at opposite ends of the cell. They uncoil, becoming long and thin. Nuclear envelope forms.

33 of 58

Cytokinesis

Cytoplasm divides. There are now 2 daughter cells.

34 of 58

Mitotic index

Number of cells with visible chromosomes / Total number of observed cells

35 of 58

Cancer

Tumour that invades surrounding tissue. Tumour is a swelling that can occur almost anywhere in the body.

36 of 58

Tumour supressor genes

When functioning normally, they slow cell division by producing proteins that stop cells dividing or cause them to self-destruct. If a mutation occurs, the gene can be inactivated, the protein isn't produced and so the cell divides uncontrollably.

37 of 58

Proto-oncogene

When functioning normally they stimulate division by producing proteins that make cells divide. When mutated they become oncogenes that can become overactive and stimulate the cells to uncontrollably divide

38 of 58

Malignant tumours

Cancer that grow rapidly and destroy surrounding tissue. Cells can break off the tumours and spread through the blood or into other sites where they form secondary tumours

39 of 58

Benign tumours

Not cancerous. They usually grow slower and are often covered in fibrous tissue that stops cells invading other tissue. Often harmless but can cause blockages, pressure on organs and become malignant

40 of 58

Metastasis

The development of a secondary malignant growth at a distance from the primary cancer site

41 of 58

Oestrogen and cancer

Oestrogen can stimulate breast cells to divide and replicate, which naturally increases the chances of mutations

42 of 58

Treatments for cancer

Chemotherapy, Radiotherapy and Surgery

43 of 58

Chemotherapy

Can be targeted to treat specific forms, have different side effects and different chemical compositions and different phases of the cycle. Doctors can time cell phases to doses of each drugs. Chemo often damages normal cells and so causes side effec

44 of 58

Chemotherapy - Alkylating agents

Keep the cell form reproducing by damaging its DNA.

45 of 58

Radiotherapy

Radiation therapy is cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumour growth. It takes days or weeks. Internal RT puts radiation inside your body. External RT aims radiation from a beam at the cancer.

46 of 58

Surgery

Removes tumours from your body, Works best for solid tumours in one area, Open - one large cut. Minimally invasive - Few small cuts with cameras.

47 of 58

Binary Fission

Prokaryoticcell division is simpler as they have singular circular DNA molecule. Occurs every 20 minutes. DNA and plasmids replicate, the membrane elongates and the membrane grows inwards.

48 of 58

How do bacteria exchange genes

Transformation-> Lysed bacterium releases DNA fragments which enter a living cell. Recombination occurs between the fragment and host. Transduction->Bacteriophage moves DNA from a donor cell to another. Conjugation-> A plasmid's DNA is donated

49 of 58

Cell membranes

Control entry and exit of substances. Most of the membrane is impenetrable to water soluble substances as it is composed of lipids, so they pass through protein passageways.

50 of 58

Fluid Mosaic Model

Phospholipids form a bilayer. Cholesterol bind to the tails to pack them more closely, proteins scattered like mosaic, phospholipids can rotate and swap. Glycoproteins communicate

51 of 58

Rate of Transport

Higher concentration gradient speeds diffusion. Thinner exchange surface speeds diffusion. Larger SA speeds diffusion. More channel proteins speeds diffusion. Aquaporins allow facilitated diffusion of water.

52 of 58

Diffusion

Exchange of substances from an area of high concentration to low. Passive processs.

53 of 58

Fick's Law

Rate of diffusion = Surface area x Concentration gradient / Thickness of exchange surface

54 of 58

Facilitated Diffusion

Uses carrier of channel proteins. Larger molecules such as glucose pass through these. Carrier-Specific molecules bind with protein, Channel - Form pore in the membrane for charged particles

55 of 58

Osmosis

Diffusion of water molecules across a partially permeable membrane. Solutions with same WP are isotonic. Pure water has highest WP of 0

56 of 58

Osmosis Key Words

Haemolyse-> Expansion of cell as a result of osmosis Crenated -> Shrinkage of cell as a result of osmosis Plasmolyse -> Shrinkage of a plant cell membrane. Hypotonic -> More water, less solute Hypertonic->Less water, more solute

57 of 58

Prasmolysis

Contraction of protoplast as a result of water loss. Incipient prasmolysis=The point at which the protoplast begins to no longer exert pressure against the wall

58 of 58

Get Revising

3.2 Cells

Other cards in this set

Card 2

Front

Back

Card 3

Front

Back

Card 4

Front

Back

Card 5

Front

Back

Comments

Similar Biology resources: