Cell Biology Flashcards
what is a eukaryotic cell?
- complex
- include all animal and plant cells
- make up organisms called eukaryotes
what is a prokaryotic cell?
- smaller and simpler
- e.g bacteria
- prokaryote (single-celled organism)
what are subcellular structures?
-different parts of the cell
what does the nucleus contain?
- genetic material
- controls activities
what is cytoplasm?
- gel like substance
- most chemical reactions occur
- controlled by enzymes
what is a cell membrane?
- holds cell together
- controls what goes in and out
what is mitochondria?
- where most aerobic respiration takes place
- transfers energy cell needs to work
what are ribosomes?
-where proteins are made
name the subcellular structure of the animal cell
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
what is a rigid cell wall of plant cell?
- made of cellulose
- supports and strengthens
what is the permanent vacuole of plant cell?
- contains cell sap
- weak solution of sugar and salts
what are chloroplasts of plant cell?
- where photosynthesis occurs
- contains green chlorophyll
- absorbs light
name the subcellular structure of the plant cell?
- rigid cell wall
- permanent vacuole
- chloroplasts
- nucleus
- cytoplasm
- cell membrane
- mitochondria
- ribosomes
what are the subcellular structures of the bacterial cell?
- cytoplasm
- cell membrane
- cell wall
- single circular strand of DNA
- small rings of DNA called plasmids
what do light microscopes use to form an image?
- light
- lenses
- see individual cells
- large subcellular structures
what do electron microscopes use to form an image?
- electrons
- higher magnification
- higher resolution
- see smaller things in more detail
what does resolution mean?
- ability to distinguish
- between two points
- higher gives sharper image
how can you calculate the magnification?
magnification=image size
real size
how do you prepare your slide to use a microscope?
- drop water middle of clean slide
- cut onion seperate layers, use tweezers peel off some epidermal tissue
- drop iodine solution
- place cover slip ontop, upright on slide, next to water droplet
- carefully tilt and lower cover specimen
why should there be no airbubbles on your slide to use under a microscope?
-obstruct view of specimen
how do you use a light microscope to look at your slide?
- clip slide onto stage
- select lowest-powered objective lens
- use coarse adjustment knob to move stage up to it
- look down eyepiece, use coarse adjustment knob image roughly in focus
- adjust focus with fine adjustment knob for clear image
- for greater magnification, swap to higher-powered objective lens and refocus
what is cell differentiation?
- cell develops different subcellular structures
- changes cell
- become specialised for its job
differentiation ability in animal cells
- lost at early stage
- after specialised
differentiation ability in plant cells
-never lost
cells that differentiate in mature animals is mainly used for…
- repairing
- replacing cells
what are stem cells?
- undifferentiated cells
- divide to produce lots more
what are sperm cells specilaised for?
reproduction
what is the function of the sperm cell?
-male DNA to female DNA
how are sperm cells specialised for reproduction?
- long tail and streamlined head help swim to egg
- lots of mitochondria provides energy needed
- enzymes in head to digest through egg cell membrane
what are nerve cells specialised for?
-rapid signalling
what is the function of nerve cells?
-carry electrical signals throughout body
how are nerve cells specialised?
- long to cover more distance
- branched connections at end to connect to others
- from network throughout body
what are muscle cells specialised for?
-contractions
what is the function of muscle cells?
-contract quickly
how are muscle cells specialised for contraction?
- long more space to contract
- lots of mitochondria provide energy needed
what are root hair cells specialised for?
-absorbing water and minerals
what are root hair cells?
- on surface of plant roots
- grows into long hair sthat stick out into soil
how are root hair cells specialised for water and mineral absorption from the soil?
-long hairs give plant big surface area
what are phloem and xylem cells specialised for?
-transporting substances
what are the functions of phloem and xylem cells?
- form phloem and xylem tubes
- transportfood and water around plants
how are phloem and xylem cells specialised for transporting substances?
- form tubes cell long joined end to end
- xylem cells: hollow in centre
- phloem cells: very few subcellular strucrure for more flow
what are chromosomes?
- contains genetic material
- found in nucleus
- coiled up lengths of DNA molecules
what do chromosomes carry?
- large number of genes
- control development of characteristics
- body cells have two copies of each chromosome from mum and dad
-
how many chromosomes are in a human cell?
-23 pairs
what is the cell cycle?
- makes new cells for growth
- development
- and repair
what is stage 1: growth and DNA replication?
- DNA spread out in long strings
- before division, cell has to grow/increase amount of subcellular structures e,g mitochondria and ribosomes
- duplicates DNA for each new cell forms X-shaped chromosomes
- each arm exact duplicate of other
what is stage 2: mitosis?
- chromosomes line up centre of cell, cell fibres pull them apart, arms go opposite ends
- membrane forms around chromosomes becoming nuclei
- cytoplasm and cell membrane divide
- two new daughter cells produced
what are daughter cells in mitosis?
- contains exact same DNA
- identical to the parent cell
what is binary fission?
-prokaryotic cells reproduce
what are the steps to binary fission?
- circular DNA and plasmids replicate
- cell gets bigger, circular DNA strands move to opposite poles of cell
- cytoplasm divides and new cell walls form
- two daughter cells produced
what are daughter cells in binary fission?
- each has one copy of circular DNA
- variable number of copies of plasmids
what conditions do bacteria need to divide very quickly?
- warm environment
- lots of nutrients
how can you use the mean division time to calculate the number of bacteria in a population?
- divide total time bacteria is producing cells by mean division time
- gives number of divisions
- multiply 2 to power of number of divisions
what is bacteria grown in?
-culture medium
what is a culture medium?
- contains carbs, minerals,proteins, vitamins bacteria needs to grow
- nutrient both solution
- or agar jelly
how do bacteria behave when grown on agar plates?
- forms visible colonies on surface of jelly
- or spreads out to give even covering of bacteria
how do you make an agar plate?
- hot agar jelly poured into Petri dishes
- when cooled and set, inoculating loops used to transfer microorganisms to culture medium
- or sterile dropping pipette and spreader even covering
- microorganisms then multiply
how are cultures of microorganisms kept at school?
- below 25ºC
- harmful pathogens likley grow above this temp
how are cultures of microorganisms kept at industrial conditions?
- incubated at higher temp
- grow faster
how can you investigate the effect of antibiotics on becaterial growth?
- place paper dics soaked in different types/concentrations of antibiotics on agar plate of even covering of bacteria, leave space between
- soak paper disc in sterile water
- antibiotic diffuse into jelly, antibiotic-resistant bacteria continues to grow but non-resistant strains will die leaving inhibition zone
- leave plate for 48h at 25ºC
- more effective antibiotic, larger inhibition zone
whay do we use a control of paper disc soaked in sterile water when investigating the effect of antibiotics on bacterial growth?
- sure that any difference between growth of bacteria around control disc and non-control
- due to effect of antibiotic alone
how do you uncontaminate Petri dishes and culture medium?
- sterilised before use
- kill unwanted microorganisms
how do you uncontaminate an inoculating loop?
- sterilised before use
- passing through hot flame
how do you make sure the Petri dish doesn’t become contaminated during use?
- after transfer bacteria
- lightly tape on lid
- stop microorganisms from air getting in
how do you prevent condensation in the Petri dish?
- store upside down
- stops drops of condensation falling onto agar surface
where can stem cells be found?
- early human embryos
- have potential to turn into different types of cells
where do adults have stem cells?
- bone marrow
- can’t turn into any type of cell
- only blood cells
how are adult stem cells used in medicine to cure disease?
- stem cells transferred from bone marrow of healthy person
- replace faulty blood cells in patient
how are embryonic stem cells used to cure people?
- replace faulty cells in sick ppl
- insulin-producing cells for diabetes
- nerve cells for paralysis by spinal injuries
what is therapeutic cloning?
- embryo made with same genetic info as patient
- stem cells won’t be rejected by patient’s body
what risks are there in therapeutic cloning?
- stem cells grown in lab may become contaminated with virus
- passed on to patient making them sicker
why are some people against stem cell research?
- human embryos shouldn’t be used as experiments
- potential human life
- some countries banned
- UK: must follow strict guidelines
why are some people for stem cell research?
- curing existing patient suffering more important than rights of embryos
- unwanted embryos from fertility clinics used otherwise destroyed
- scientists should concentrate on finding and developing other sources so ppl can be helped without using embryos
where are stem cells found in plants?
- meristems
- throughout plant’s life cells can differentiate
what can meristems be used for?
- produce clones of whole plants quickly and cheaply
- grow more plants of rare species
- grow crops of identical plants that have desired features for farmers e.g disease resistance
