1.1 Introduction to Cells Flashcards
What is the cell theory? (3)
- All living things are made of cells
- Cells are the smallest unit of life
- All cells only come from pre-existing cells
What does every cell have? (3)
- A membrane
- to separate contents from the outside
- Genetic material, i.e. DNA/RNA
- An energy release system
- to power the whole cell
What three examples test the cell theory? (3, SPELLING)
- Striated muscle
- Aseptate hyphae
- Giant Algae
Describe the striated muscle. (2)
How does it challenge the cell theory? (2)
- type of tissue (muscle fibre) where the fibres are similar to cells
- cells are surrounded a plasma membrane, those within the membrane fuse together
- causes fibres to become very long (~30mm)
- contain many nuclei within a single membrane
- challenges idea that cells always function as individuals
Describe the aseptate hyphae. (2)
How does it challenge the cell theory? (2)
- fungi may have hyphae (thread-like structures)
- hyphae are separated into cells by septa (internal walls)
- some fungi don’t have septa
- continuous cytoplasm along the entire hyphae
- long structure similar to a cell
- many nuclei present
- challenges idea that living structures are made of discrete cells
Describe the giant algae. (1)
How does it challenge the cell theory? (2)
- seem to be unicellular
- very large structures (≤10cm)
- challenges idea that larger organisms are always made of many tiny cells
What is the equation for magnification? (1)
I = AM Image = Actual x Magnification
Convert 1mm to micrometers and nanometers. (2)
1mm = 1,000 micrometers 1mm = 1,000,000 nanometers
Outline the functions of life. (7)
Metabolism - all the enzyme catalysed reactions within an organism or cell
Response - a reaction by the living organism to changes in the external environment
Homeostasis - maintaining a constant internal environment within tolerable limits
Growth - increasing in cell size or number of cells
Reproduction - producing offspring either sexually or asexually
Excretion - removing waste products of metabolism and other unimportant materials from an organism
Nutrition - obtaining food to provide energy and the materials needed for growth
Which two unicellular organisms are studied? (2, SPELLING)
- Paramecium
2. Chlamydomonas
Which organism is a heterotroph, Paramecium or Chlamydomonas? (1)
Paramecium is heterotrophic, Chlamydomonas is autotrophic
How does the Paramecium consume, and what does it feed on? (4/5)
- engulfs food particles in vacuoles
- also digests food in vacuoles
- nutrients get absorbed into the cytoplasm
- Paramecium feed on microorganisms
- eg. bacteria, algae, yeasts
How does the Chlamydomonas synthesise organic molecules? (2/3)
- it has a large chloroplast for photosynthesis
- CO2 can be converted into necessary compounds
- carbon compounds from other organisms can be absorbed too
- through cell membrane
What structures do Paramecium and Chlamydomonas have projecting out from the cell? (3)
Paramecium: beating cilia propels the cell as response to environment
Chlamydomonas: flagella moves the cell towards brighter regions (sensed by light-sensitive ‘eyespot’)
What type of reproduction (sexual/asexual) do Paramecium and Chlamydomonas carry out? (2)
Both carry out sexual and asexual reproduction
- though asexual is more common among Paramecium
How do Paramecium and Chlamydomonas excrete waste products? (1)
Waste products diffuse out through the plasma membrane
What are emergent properties? (1)
Properties that emerge from the interaction of cellular components, or characteristics of the whole organism
What is the purpose of cell differentiation? (2/3)
- different cells can perform different functions
- division of labour
- more efficiency as cells develop their ideal structure for their function
What are specialised cells? (1)
Cells that perform one specific function
How do cells become specialised? (4)
- all genes are present in all body cells
- specialised cells have some genes switched off
- can’t make those proteins
- genes permanently off
- specialised cells have some genes switched off
- different sequences of genes expressed in different cell types
What are stem cells? (2)
- cells that can divide countless number of times
- not fully differentiated
What are the four different types of stem cells, where are they found, and what is the extent of their differentiating abilities? (7, not necessary but helpful terminology)
Totipotent
- can differentiate into every cell type
- from zygote
Pluripotent
- can differentiate into every cell type EXCEPT placenta
- from blastocyst inner cell mass
Multipotent
- can differentiate into a number of different but closely related cells
- from bone marrow or cord blood
Unipotent
- cannot differentiate, but capable of self renewal
- many places around the body
What are the three studied stem cell sources? (3)
- embryo
- cord blood
- adult
What are the two studied ways of using stem cells? (2, SPELLING)
- Stargardt’s disease (Stargardt’s macular dystrophy)
- Leukemia
