Cells Flashcards
What is the definition of eukaryotic cell?
A cell with dna in the nucleus and membrane bound organelles, bigger than prokaryotic cells
What is an example of a membrane bound organelle?
Mitochondria
How are prokaryotic cells different from eukaryotic cells?
They are smaller and have no nucleus, rather the dna is floating about in the cytoplasm. Some dna are in plasmids
What is the function of nuclei?
Stores genetic information and controls the activities of the cell
What is the function of cytoplasm?
Where the chemical reactions take place
What is the function of ribosomes?
Site of protein synthesis
What is the function of the vacuole?
Helps the cell keep its shape and stores water
What is the function of the cell wall?
Protects the cell. Very rigid and sturdy, and made of cellulose
What is the function of the chloroplasts?
Contains chlorophyll and is a site of photosynthesis which produces energy from sunlight, chloroplasts make the plant green
What is the function of pili?
For sticking to surfaces and other cells
What is the function of plasmids?
Extra lots of circular dna, can be for antibiotic resistance. Some produce toxins
What type of organelles do animal cells have? (5)
Nuclei, mitochondria, ribosomes, cell membrane, cytoplasm,
What type of organelles do plant cells have? (8)
Nuclei, mitochondria, ribosomes, cell membrane, cytoplasm, Chloroplasts, vacuole, cell wall
What type of organelles do prokaryotes have? (6)
Cell wall, plasmids, pili, cytoplasm, capsules, flagella
What is the function of flagella?
Movement
What is the cell wall (membrane?) in prokaryotes made out of?
peptidoglycan
Pre-1970, how were living things classified?
Into five kingdoms, based on observable traits
Post-1970, how were living things classified?
Into three domains
What are archaea?
Small, single called organisms that live in extreme environents (extremophiles)
Why were archaea and bacteria separated into two separate domains?
woesse decided that if these organisms (archaea) lived in extreme environments, they must be different
What are the differences between archaea and bacteria?
- dna sequencing shows their DNA is very different
- archaea ribosomes have nucleic acids more like eukaryotes
What kind of places can archaea live in?
Salt planes, very hot water, deep water, etc
What are the parts of a microscope? (4)
Eyepiece lens, objective lens, fine and coarse focusing knobs
What is the eyepiece lens for?
The first stage of magnification, where you look into the microscope
What is the objective lens for?
second stage of magnification,changes how closely magnified the image is.
What is the fine + coarse focusing knobs for?
Fine-tuning the image; viewing the details and rough focusing respectively
What is the definition of magnification?
The ability of a lens or other optical instrument to magnify (enlarge) the size of something in the optical
What is the definition of resolution?
The ability of a microscope to distinguish between two adjacent points as seperate
What is the definition of maximum resolution?
The smallest distance between two points, at which they can be recognised as separate entities. The better the resolution, the easier you can view & identify finer details
Who was Ernst Ruska?
A German physicist who won the 1986 Nobel
physics prize for his work on electron optics, including the invention of the electron microscope.
Who was Anton von Leeuwenhoek ?
A Dutch businessman and scientist, and the first person to see bacteria after looking closely at water with a microscope.
Some of his other discoveries include blood and sperm cells
Who was Robert Hooke ?
The first person to see a microorganism with a microscope. He named cells and wrote a book (micrographia) about his findings.
Who invented the electron microscope?
Ernst Ruska
How can you calculate total magnification in a microscope? (And which variables are fixed and which can change?)
Magnification of eyepiece lens* x magnification of objective lens**
- fixed
- *can change between x4 x10 x40 x10p
What are the disadvantages of electron microscopes?
Can only see in black and white, very expensieve, very big, not portable, can either be SEM or TEM, thing you’re looking at must be dead
What are the disadvantages of light microscopes?
Less magnification and resolution
What are the advantages of light microscopes?
Portable see in colour specimen can be alive cheaper can be used by anyone smaller
What are the advantages of electron microscopes?
Greater magnification and resolution
can see inside cell
no complex lighting
What are the two types of electron microscope?
Scanning electron microscopes (SEM) and transmission electron microscopes (TEM)
What are movement, respiration, growth, reproduction, excretion and nutrition?
Life processes
What do cells group together into?
Tissues
How many times can an electron microscope magnify up to compared with a light microscope
2 million times (electron)
2,000 times (light)
How does the electron microscope work?
Uses electron beams instead of light beams, and the electrons bounce off surface of a specimen that has a very thin coating of a gold-like metal
What does a scanning electron microscope do?
The electrons scan a sample’s surface
What does a transmission electron microscope do?
The electrons penetrate a sample’s surface to see inside
“Explain how electron microscopes have increased out knowledge of sub cellular structures.”
“An electron microscope has a much higher magnification and resolving power, meaning it can be used to study cells in more detail. Scientists can now see and understand sub cellular structure.”
What is resolving power?
The ability of a microscope to distinguish between two adjacent points (resolution)
What is the smallest thing we can see? (With the naked eye?)
0.04mm
How do you calculate magnification of an image?
Image size / actual size
How do you calculate image size?
Magnification x actual size
How do you convert out of standard form? (Example of 1.26 x 10^5)
The power of ten is how many times you move the decimal place to the /right/. If the power is negative, move to the /left/ instead.
Why might mitochondria look different in different slides?
There might be mutations, different slices, natural differences or damages.
What are stem cells?
Stem cells are unspecialised cells with the ability to duplicate / or duplicate and specialise
What type of cells can embryonic stem cells differentiate into?
Any type
What type of cells can umbilical cord stem cells differentiate into?
Blood
What type of cells can normal stem cells differentiate into?
The type of cell from the tissue they are found in
Where are embryonic stem cells found?
In the blastocyst, 3-5 days after fertilisation
What is an immunosuppressant?
A drug that supremes an immune system so it doesn’t reject foreign tissue such as a transplanted heart
Where are stem cells found in plants?
The meristem- the roots and shoots
What diseases are stem cells being used to cure?
Parkinson’s and diabetes, specifically type 1
Also age related sight loss and paralysis
What are therapeutic stem cells?
“Fake” stem cells that are grown from a half a nucleus of a patient and a donated egg cell (or vice versa, if the patient is female)
This means that the patient doesn’t have to take immunosuppressants
Why can plant stem cells be useful?
Creating plants immune to disease, protecting endangered species, indentical plants for research,
What is binary fission?
A type of asexual reproduction found in bacteria, where one organism splits to become two
