1.1 Introduction to cells Flashcards
What does the cell theory state?
- Cells are the fundamental building blocks of all living organisms
- The smallest organisms are unicellular - they consist of just one cell
- Larger organisms are multicellular - they are composed of many cells
What are the 4 common features of cells?
- Each living cell is surrounded by a membrane, which separate the cell contents from everthing else outside
- Cells contain genetic material which sotres all of the instruction needed for the cell’s activity
- Many of these actvities are chemical reactions, catalysed by enzymes produced inside the cell
- Cells have their own energy release system that powers all of the cell’s activities
What are the 3 core ideas of the cell theory?
1) cells are the smallest unit capable of independent life, organelles cannot survive alone
2) living things are composed of cells. Cells are the fundamental building blocks of all living organisms (unicellular and multicellular)
3) cells only arise from pre-existing cells by the process of cell division (mitosis and meiosis and binary fission)
Why is the cell theory a theory?
Because it is widely excepted but not 100% sure
How could you test the cell theory?
By looking at different organisms
What three types of cells/tissues challenges the cell theory? And how?
- Striated muscle fibers
- Aseptic fungal hyphae
- Giant algae
How does striated muscle fibres challenge the cell theory?
- a muscle cell
- they merged to form long muscle fibers with multiple nuclei.
- They challenge the idea of cells always functioning as a autonomous (independent) unit
How does Aseptic fungal hyphae challenge the cell theory?
- Aseptate differs from a septate hypha because it does not have septas (cross-walls), meaning they have a continuous cytoplasm with multiple nuclei.
- This challenge is the idea that the cell is a single unit.
How does the giant algae challenge the cell theory?
- Giant algae is a unicellular organism.
- Most algae are microscopic and unicellular but the giant algae can grow to 100 mm in width yes still a single cell.
- This challenge is the idea that larger organisms are always made up of many multiple cells.
What is the mnemonic for the 7 functions of life?
MR H GREN
What are the 7 basic functions of life?
All living things carry out these functions:
M - Metabolism
R - Response
H - Homeostasis
G - Growth
R - Reproduction
E - Excretion
N - Nutrition
What is metabolism as a function of life?
Chemical reactions inside the cell, including cell respiration to release energy
What is response as a function of life?
The ability to react to changes in the environment
What is homeostasis as a function of life?
Keeping conditions inside the organism within tolerable limits (water and pH etc)
What is growth as a function of life?
An inversible increase in size
What is reproduction as a function of life?
Producing offspring either secually or asexually
What is excretion as a function of life?
Getting rid of the waste products of metabolism
What is nutrition as a function of life?
Obtaining food, to provide energy and the materials needed for growth
What is the difference between egestion and excretion
Excretion is in the blood and its the procces of getting rid of waste product from metabolic reactions
Egestion is everything you ate thats not absorbed. It is basically the passing of undigested food (faeces)
Compare the nutrition function of paramecium and Chlamydomonas
Paramecium feeds on smaller organism by ingesting and digesting them in vesicles (endocytosis)
Chlamydomonas produces its own food by photosynthesis using a chloroplast that occupies much of the cell
Compare the growth of Paramecium and Chlamydomonas
Paramecium increases in size and dry mass by accumulating organic matter and minerals from its food.
Chlamydomonas increases in size and dry mass due to photosynthesis and absorption of minerals
Compare the response of Paramecium and Chlamydomonas
Paramecium reacts to stimuli, e.g. reverses its direction of movement when it touch as a solid object
Chlamydomonas react to stimuli, e.g. senses where the brightest light is with its eyespot and swim towards it
Compare excretion of Paramecium and Chlamydomonas
Paramecium expels waste products of metabolism, e.g. CO2 from respiration diffuses out of the cell
Chlamydomonas expels waste products of metabolism, e.g. oxygen for photosynthesis diffuses out of the cell
What functions do paramecium and Chlamydomonas have in common?
Metabolism, homeostasis and reproduction
MHR