Cell theory (CH 4.1) Flashcards
Who was the first person to observe cells?
- Robert Hooke in 1655
- Named shapes he saw in cork Cellulae (small rooms)
Who was the first person to observe LIVING cells?
- Anton Van Leeuwnehoek
- Termed “animacules”
What are 3 principles of Cell Theory?
- All organisms are composed of one or cells &; life processes of metabolism &’ heredity occur within these cells
- Cells are the smallest living things= basic units of organization of all organisms
- Cells come from the division of previous cells
Why are cells so small?
-Reasons related to diffusion of substances in &; out of them
What variables affect the rate of diffusion?
- Surface area
- Temperature
- Concentration gradient of diffusion subject
- Distance over where diffusion must occur
What is the relationship between the size of the cell &; diffusion?
- Directly proportional
- The bigger the cell, the longer the length of time for diffusion from outside of cell membrane to inside of cell
- Larger cells need to synthesize more macromolecules= higher energy needed= higher waste produced
What does the rate depend on between metabolic waste being removed &; transport through cell membrane?
-Distance of cell membrane &; the area of cell membrane available
What is Surface-Area to Volume Ratio?
- As cell size increases, it’s volume increases more rapidly than the surface area
- For spherical cells, surface area= Radius^2 &; volume= Radius ^3
Why are smaller cells better than bigger cells?
-Have more surface area per unit of volume= control of contents over contents is more effective
What is Resolution?
-Minimum distance between two points can be apart &; still be distinguished as two separate points
How do Modern Light Microscrope operate?
- Operate w/ visible light
- Use 2 magnifying glasses to achieve high magnification &; clarity
- 1st lense= focuses image of the 2nd lens &; magnifies it &; focuses on the back of the eye
What causes images from a microscope to overlap?
- Objects being closer than a few hundred nanometers
- Light beams reflecting off the object causes the image to overlap each other
How do you reduce overlapping of images for a microscope?
-Using electron beams because they have a shorter wavelength= has 1000x more power than a light microscope
What are the 2 kinds of electrons microscopes?
- Transmission electron microscope
- Scanning Electron Microscrope
What is Immunohistochemistry?
- Strains that bind to particular types of molecule to increase constrast between different cellular components
- Using antibodies generated in animals
What are the 4 major features that all cells have in common?
- Nucleoid/ Nucleus where genetic material is stored
- Cytoplasm
- Ribosomes to synthesize proteins
- Plasma membrane
Where does DNA lie in Prokaryotes?
-Lies in the center of the cell= Nucleoid (not segregates from rest of the interior membrane
Where does DNA Eukaryotes?
-Contained in nucleus= surrounded by double-membrane structure= Nuclear Envelope
What is a Cytoplasm?
- Contains all sugars, amino acids, proteins the cell uses to carry out its everyday activities
- More like jell-o bc it has a high concentration of proteins &; other macromolecules
What are Organelles?
- Macromolecular structures that have their own specialized function
- Located in cytoplasm
What is Cytosol?
- It’s the part of the cytoplasm that contains organic molecules &; ions in the solution
- Distinguishes it from the organelles in the cytoplasm
What is a Plasma Membrane?
- Phospholipid bilayer 5-10nm thick
- Has proteins embedded in it
- Tail to Tail packing
What are the different types of proteins & what are their jobs?
- Responsible for cell’s ability to interact w/ environment
- Transport Proteins= helps ions &; molecules move across membrane
- Receptor Proteins=Induce changes within the cell when they come in contact w/ specific molecules which can function as markers that identify the cell as a particular type
What are the 6 (or 5) features of life?
- Complex organization
- Responds to external environment
- Maintains internal environment (homeostasis)
- Carries out metabolism & growth (energy metabolism using ATP)
- Reproduces & maintains heredity which leads to
- Adaptation to environment & evolves
What does Cell theory explain?
- Our definition of life
- Cells provide complexity, organization, responsiveness, homeostasis, metabolism, & growth
- Explains continuity features= Reproduction, heredity, adaptation to environment & evolution
What is the size range for a cell?
-1 micrometer to 1 nm (100 fold change)
Why is the size range of a cell size ideal?
- If it’s too small (smaller than 1 micrometer)= not enough room for molecules especially DNA= hard to keep life going
- If its too big= has to much waste to export & has to import hella food which is based on the volume of the cell & there isn’t enough surface area
What are the special exceptions to the cell size range & why?
- Eggs!
- Bc they are filled with the materials needed by the special mechs
What is the difference between Eukaryotes & Prokaryotes?
- Euks= have membrane-bound nucleus & internal membrane system
- Prokary= don’t have nucleus & internal membrane system
What are considered to be Non-living & why?
- Viruses, individual molecules, & individual organelles
- Organelles can keep working after they’ve been separated from the cell
