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Biology > Cell diversity > Flashcards

Cell diversity Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Why do multicellular organisms need to be specialised?

A

Multiple tasks simultaneously eg. digest, reproduce, protect against disease.
Cells evolved to have more/less organelles and structures became specialised.

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2
Q

How are erythrocytes specialised?

A

Transport oxygen from lungs to body cells. Biconcave shape - large SA. Oxygen can diffuse in and reach all parts inside cell.
No nucleus - more space for haemoglobin.
Developed cytoskeleton - flexibility. Can bend through narrow capillaries.

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3
Q

How are neutrophils specialised?

A

Larger than erythrocytes, travel to infection sites by chemotaxis (due to receptors for inflammatory chemicals on surface).
Multi lobed nucleus - move and engulf material easier.

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4
Q

How are sperm cells specialised?

A

Tail allows them to swim - movement requires ATP from many mitochondria.
Long and thin - streamlined.
Specialised lysosome = acrosome containing lysozyme. Digest out coating of egg cells - nucleus can enter egg for fertilisation.

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5
Q

How are epithelial cells specialised?

A

Squamous epithelial cells in alveoli. Thin and flat - decreases diffusion distance - rapid gas exchange.
Ciliated epithelial cells in trachea. Tiny hair-like structures = cilia. Move mucus along.

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6
Q

How are palisade cells specialised?

A

Long and cylindrical - light absorbed.
Tightly packed - gaps between. Allow CO2 through for photosynthesis.
Many chloroplasts - towards edge of cells by big vacuole. CO2 has shorter diffusion distance.

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7
Q

How are guard cells specialised?

A

Cell walls are thicker in middle but thinner and more flexible at the tips. Contain chloroplasts - make ATP but no sugars.

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8
Q

What is the main function of guard cells?

A
  1. Guard cells make ATP through stage 1 of photosynthesis - lowers water potential.
  2. Water moves into guard cell and pushes against the sides - swell.
  3. Paired guard cells are pushed apart - open stoma. Gas exchange can occur.
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9
Q

How are root hair cells specialised?

A

Protein pumps on plasma membrane - transport minerals in. Lowers water potential, so water follows by osmosis.
Protein pumps require ATP - lots of mitochondria.
Protrusions that increase SA for protein carriers (active transport) and water/ion absorption.

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10
Q

What is a tissue?

A

A group of cells that work together to perform same function.

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11
Q

What are the 4 main tissue types?

A

Epithelial, connective, muscle, nervous.

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12
Q

What is epithelial tissue?

A

Forms the lining between different areas of space in body eg. skin, airways. Protects cells, absorb, secrete and excrete molecules.

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13
Q

What is the epithelial tissue made up of?

A
  • Tightly packed epithelial cells joined by tight junctions and proteins.
  • Blood vessels not run through - get O2 and nutrients from tissue fluid.
  • Exposed to extreme conditions - often damaged. Short cell cycles.
  • Some have smooth surfaces, others have projections.
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14
Q

What are examples of epithelial tissue?

A

Squamous - single layer of flat cells.
Ciliated - layer of cells covered in cilia.

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15
Q

What is connective tissue?

A

Separated and connected cells, withstand forces. Made of non living proteins and carbs - form extracellular matrix.
eg. elastin, collagen, carbs including hyaluronic acid (traps water). Connecting tissue eg. blood and bone.

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16
Q

What is cartilage?

A

Connective tissue in joints and around soft tissue. When matrix forms, develops into mature cartilage.
3 types: hyaline, fibrous, elastic.

17
Q

What is muscle tissue?

A

Controls movement so is very metabolically active with good blood supply. Made of muscle fibres and myofibrils.
3 types: skeletal, cardiac, smooth.

18
Q

What is an organ?

A

A group of tissues that work together to perform a function.

19
Q

What is vascular tissue?

A

Transport - xylem and phloem in vascular bundles.
Plants also have epidermal tissue with cuticle.

20
Q

What is an organ system?

A

A group of organs that work together to perform an overall life function.

21
Q

What are examples of stem cell treatments?

A

Bone marrow - any type of blood cell. Can be used to treat blood diseases.
Diabetes treated with pancreatic cells to become beta cells - make insulin.
Neurodegenerative disorders could be treated by stem cells differentiating into neurones.

22
Q

How are stem cells important in research?

A

Test drugs - avoid animal testing but can asses for side effects.
Study how animals/humans develop - study differentiation.
How diseases develop and can be prevented.

23
Q

What is regenerative medicine?

A

Stem cells can be grown into specific shape + cell type to be transplanted.
If use patient’s cells, no need for immunosuppressant drugs.

24
Q

What is a stem cell?

A

Undifferentiated cells that can express all genes and divide by mitosis.

25
Q

What is differentiation?

A

The process by which cells become specialised for different functions.

26
Q

How do stem cells develop?

A

Certain genes are switched on/off. Cells take on individual characteristics and adapt to functions when they mature and become specialised.
Cell differentiation.

27
Q

What is a pluripotent stem cells?

A

Can differentiate into almost any cell type except placenta cells. eg. embryonic and foetal.
Undergo mitosis continuously for growth and repair.

28
Q

What are sources of stem cells?

A

Embryonic - any cell type.
Umbilical cord blood - blood cells.
Adult stem cells - small selection of cell types to replace damage.
Pluripotent can be induced (iPS). Made in lab by switching on certain genes normally expressed.

29
Q

What is meristem tissue?

A

An area of unspecialised cells in a plant which can self-renew and differentiate.
Found in cambium of vascular bundles, root and shoot tips.

30
Q

What are features of meristem?

A
  • Thin cell walls - divide easily.
  • No chloroplasts and small vacuole - no photosynthesis.
  • When divide, can differentiate into specialised plant cells.
31
Q

What does the differentiation of meristem tissue into xylem involve?

A
  • Deposition of lignin in cell wall (strong and waterproof).
  • Ends of xylem cells break down in differentiation so water etc. travels unobstructed.
32
Q

What does the differentiation of meristem tissue into phloem/companion cells involve?

A
  • Sieve tubes carry phloem sap, few organelles and have sieve plates
  • Companion cells have many mitochondria so can actively pump sugars into sieve tubes (ATP source).

Biology (32 decks)

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