Cells Flashcards
The cell theory
- living things are composed of cells
- they are formed by pre-existing cells
- they derive their structure, function and organization from their cells
Surface area and cells
- the shape of cells are small in order to allow there to be a greater surface area to volume ratio
- this is to have more area for nutrients to diffuse into the cell
Cell membrane
- forms a protective barrier around the cell
* selectively permeable to regulate what enters and leaves the cell
Cytoplasm
• contains nutrients required by the cell to carry its life processes
Nucleus
- control center organelle
- controls activities such as growth and reproduction
- contains DNA
Nucleolus
- the inner section of the nucleus
* produce ribosomes
Vacuoles and vesicles
- membrane-bound organelles that store nutrients and waste
* plant cells have one large central vacuole
Mitochondria
- releases the energy of food for the cell in carbon dioxide and water
- cellular respiration
Lysosomes
- where digestion takes place
- filled with enzymes
- break down invading bacteria and damaged cells
Golgi apparatus
- receives proteins from endoplasmic reticulum
* modifies, sorts, and packages protein into vesicles for delivery
Rough endoplasmic reticulum
- carries material throughout the cell
- makes proteins
- contains ribosomes
Ribosomes
- may be attached to the rough endoplasmic reticulum
* where proteins are produced
Smooth endoplasmic reticulum
- carries material throughout the cell
* produces fats and oils
Cytoskeleton
- internal network of fibers
* helps maintain the shape
Cell wall
- found only in plant cells
* rigid frame that provides strength, protection, and support
Chloroplasts
- found only in plant cells
- contain chlorophyll
- photosynthesis = make food from carbon dioxide and water
- used for the growth of the plant
Centrosomes
- found only in animal cells
- guide the movements of chromosomes in cell division
- contain centrioles
Interphase
- cells are doing their normal activities (acquiring nutrients, eliminating waste, growth)
- their DNA is in the form of chromatin
- the DNA replicates, forming two copies
Prophase
- the nucleus dissolves
- chromatin thickens into chromosomes
- each chromosome has two identical copies called chromatids and are attached by centromeres
- nucleoli disappear
- centrioles (only in animal cells), move towards the poles of the cell
- spindle fibers form that radiate outward from the centrioles
Metaphase
- the chromosomes line up along the equator of the cell
* they appear lined up in the middle of the cell
Anaphase
- the centromeres break, allowing the chromatids to separate into new chromosomes called daughter chromosomes
- the daughter chromosomes follow the spindle fibers toward the poles of the cell
Telophase
- nuclear membranes start forming around the daughter chromosomes
- nucleoli reappear
- the spindle fibers dissolve
Cytokinesis
- redistribution of existing cytoplasm and organelles to the new daughter cells
- animal cell membranes pinch in around the centre, forming a cleavage furrow
- plant cell walls cannot pinch like this, so a cells plate forms between the daughter cells, and later hardens into a new cell wall
Generalist cells
• the single cell of unicellular organisms has to be able to carry out all the functions of life = locomotion, gas exchange, absorption of food
Multicellular organisms
- as organisms grow, their cells must divide to provide a better surface area to volume ratio
- therefore larger organisms will contain more than one cell
Cell differentiation
- multicellularity allows the specialization of cells for particular tasks
- specialized cells do specific jobs better, at the expense of other functions
- this makes different types of specialized cells dependent on each other
Types of stem cells
- totipotent = can produce every differentiated cell in an organism
- pluripotent = can produce any fetal or adult cell type, except the placenta
- multipotent = can produce a few different types of cells
