Cell Structure and Division Flashcards
What are eukaryotes?
- plant cells
- animal cells
- has cell membrane, cytoplam, nucleus
- genetic material made of DNA
What subcellular structures does an animal cell have?
- cell membrane = controls what goes in and out of cell, partially permeable
- ribosome = protein synthesis
- cytoplasm = suspends cell structures, site of cell structures
- mitochondria = aerobic respiration
- nucleus = controlls cell processes, DNA stored here
What subcellular structures does a plant cell have?
- cytoplam
- cell membrane
- cell wall = strengthens cell, made of cellulose
- nucleus
- ribosome
- mitrochondria
- cell vacuole = filled with cell sap, stores nutrients and supports cell
- chrloroplasts = chlorophyll, traps light energy for photosynthesis
What is the difference between eukaryotes and prokaryotes?
- pro. = smaller than euk.
- no nucleus
- DNA loop floating in cytoplasm
- may have small rings of DNA = plasmids
What are the levels of organisation in an organism?
- cells
- tissues
- organs
- organ systems
What adaptations does phloem cells have to perform its function?
what is its function!!!!
- elongated cells to trasnport sugars over long distances
- companion cells have many mitochondria for active transport
transport sugars made in leaves to rest of plant
What adaptions do xylem cells have to perform their function?
function?
- hollow tubes (lumen) - no end walls to allow water and minerals flow
- lignin in walls to provide strength and support
transports water and mineral ions throughout plant
What adaptations do sperm cells have to perform their function?
function!
- enzymes in head to digest coating of egg
- many mitochondria to provide energy for swimming
- tail for swimming
carry genetic material to egg cell
What adaptations does a muscle cell have to perform their function?
function!!!!!
- lots of mitochondria to provide energy for contraction
- protein fibres shorten to make cells contract, shortens structure
provide movement
What adaptations does a nerve cell have to perform its function?
- dendrites make connections with other cells
- fatty myelin sheath speeds up impulse
- axon = long, carries impulses across body
cary electrical impulses around body
Describe differentiation in animal cells throughout its life
- most types of cells differentiate at early stage
- early embryo cells = unspecialised
- mature animals = repair of damaged tissues/ replacement of worn out cells
Describe differentiation in plant cells throughout its life
- cells continue to divide and differentiate throughout life of plant
- **meristems **responsible for division
What is magnification?
- how many times bigger an image is than the object that is viewed
What is resolution?
- measure of smallest distance between two points that still can be distinguished
poor resolution = blurred with magnified
How do you calculate magnification?
size of image/ size of real object
How are unwanted microoganisms kept from contaminating a culture?
- sterilise petri dishes + culture media before use
- inoculating loops passed through flame
- lid stops microorganisms falling into agar from air (fixed in place with tape)
- work near a flame
How do bacteria multiply?
- binary fission
When were the first light microscopes developed?
400 years ago
When was the electron microscope invented?
and what were they like?
- 1930s
- higher magnification
- higher resolution
- can see sub-cellular structures
What kind of bacteria is used for the investigation of comparing different antibiotics or antiseptics?
- bacterial lawn on agar distributed by spreader
- agar becomes cloudy
- no bacteria = clear agar
How are the antiseptic or antibiotics placed in the agar?
- small paper discs soaked with solutions of antibiotics/ antiseptics
What is the clear area around the paper disc called?
- zone of inhibition
How do you compare different antibiotics or antiseptics?
- measure 2 diameters of clear area
- calculate mean (more accurate)
Describe the cell cycle
1) cell growth = number of subcellular structures increase
2) DNA replicates = forms 2 identical copies of each chromosome
3) Mitosis = chromosomes separate, nucleus divides in 2
4) Cell division = cytoplasm + cell membrane divides = 2 new identical cells made
Describe the stages of mitosis
- newly replicated chromosomes joined together
- move to centre of cell
- chromosomes pulled apart, moved to opposite ends (poles) of the cell
- nucleus divides
What is mitosis used for?
- growth
- repair of worn out or damaged cells
What are stem cells?
- undifferentiated cells that divide to make new cells
What do cells in an early embryo do and how do scientists use them?
- unspecialised
- differentiates to produce all types of cell needed to make adult organism
- clone cells from early human embryos in lab
- made to differentiate into different types of cells
What are stem cells in adult animals used for?
- can only produce limited range of cell types
- replace worn out or damaged cells
bone marrow = exception, can product many types of cells
Describe the process of therapeutic cloning
- egg cell nucleus replaced with patient’s nucleus from cell
- embryo made that has same genes as patient
- stem cells removed to treat patient
- not rejected, since it has same genes as patient
What are the advantages of therapeutic cloning?
- may treat diseases and replace faulty organs
- wider range of cells produced than adult stem cells
- stem cells not rejected by patient
- many cells produced, some used in research
What are the disadvantages of therapeutic cloning?
- stem cells may transfer viral infection
- ethical or religious objections (kills embryo?)
- human eggs in short supply, collecting = risks
- side effects of stem cells not known
What are the benefits of growing plants from stem cells?
- large numbers of new plants produced quickly + cheaply
- rare species cloned prevent extinction
- crop plants with useful features (eg disease resistance) -> cloned = large number of useful plants for farmer
What is diffusion?
- net movement from an area of higher concentration to lower concentration
What affects the rate of diffusion?
- concentration gradient = increases chance of particles moving from high concentration to low concentration
- temperature = increases kinetic energy of particles, moves faster
- surface area = more membrane for particles to move across
How is the small intestine adapted for efficient diffusion?
- vili and microvili increase SA
- wall of vili = thin
- good blood supply
What are the lungs adapted to increase the rate of diffusion?
- alveoli increase SA
- thin walls
- surrounded by capillaries
- good ventilation (conc. grad.)
What is osmosis?
- diffusion of water from dilute solution to more concentrated solution through a partially permeable membrane
How are fish gills adapted to increase diffusion?
- gill filaments increase SA
- filaments well supplied with blood
- thin walls reduce diffusion pathway
- good ventilation
How are roots and leaves of plants adapted for efficient diffusion?
- extension of root hair cells = high SA
- large internal surface area for diffusion
- thin = reduces diffusion distance
What is active transport?
- moving substances from dilute solution to more concentrated solution
requires energy from respiration
What is active transport used for in plants?
- mineral ions from soil to root hair cells
What is active transport used for in animals?
- absorbing sugar in small intestine
