cells Flashcards
What is the basic unit of life?
The cell.
True or False: All living organisms are made up of cells.
True.
What structure controls the entry and exit of substances in a cell?
The cell membrane.
Fill in the blank: The _____ is the jelly-like substance inside the cell.
cytoplasm.
What organelle is responsible for energy production in the cell?
Mitochondria.
Which type of cell lacks a nucleus?
Prokaryotic cell.
What is the function of ribosomes?
Protein synthesis.
True or False: The endoplasmic reticulum is involved in lipid and protein synthesis.
True.
What organelle is known as the ‘powerhouse of the cell’?
Mitochondria.
Fill in the blank: The _____ is a network of protein filaments that helps the cell maintain its shape.
cytoskeleton.
What is the function of the Golgi apparatus?
Modifying, sorting, and packaging proteins.
Which organelle is involved in the digestion of waste materials?
Lysosomes.
True or False: Chloroplasts are found in animal cells.
False.
What is the primary function of the nucleus?
To store genetic information.
What type of cell contains chloroplasts?
Plant cell.
Fill in the blank: The _____ is a double membrane that surrounds the nucleus.
nuclear envelope.
What is the main component of the cell membrane?
Phospholipids.
True or False: The cell wall provides structural support in animal cells.
False.
What is the function of the vacuole in plant cells?
Storage of substances and maintaining turgor pressure.
Which structure is responsible for detoxifying harmful substances in the cell?
Smooth endoplasmic reticulum.
What is the role of the plasma membrane?
To regulate the movement of substances in and out of the cell.
Fill in the blank: The _____ is involved in the synthesis of ribosomal RNA.
nucleolus.
What is the difference between rough and smooth endoplasmic reticulum?
Rough ER has ribosomes on its surface; smooth ER does not.
True or False: All cells have a cell wall.
False.
What is the function of peroxisomes?
To break down fatty acids and detoxify harmful substances.
What structure is involved in cell division in animal cells?
Centrioles.
Fill in the blank: The _____ helps in the transport of materials within the cell.
endoplasmic reticulum.
What is the primary role of cytoplasm?
To provide a medium for chemical reactions and support organelles.
what organelles are in a eukaryotic cell
- nucleus
- nucleolus
- nuclear pore
- ribosomes
- mitochondria
- rough and smooth endo plasmic reticulum
- cytoplasm
- cell membrane
- golgi apparatus
rules of biological drawings
- no shading
- single, continous lines
- labels
- no crossing over
magnification / scale bar used
How do you make a temporary mount of plant tissue to observe starch grains using an optical microscope
1) add a drop of water to a glass slide
2) obtain a thin section of plant tissue to place on the slide
3) stain starch grains blue-black with iodine
4) using a mounted needle, lower the cover slip down onto the sample, avoiding trapping any air bubbles
what is the order of magnitude
nm < um < mm < m
A nm is 1000x smaller than a micrometre, you could fit 1000nm in 1 um
what is the difference between magnification and resolution
magnification is making objects appearance increase in szize whereas resolution is the ability to distinguish between two separate points
differences between an optical and electron microscope
o = uses light
o = lower resolution due to longer wavelength
o = only the nucleus, cytoplasm and cell walls can be seen
o = can view live specimens
o = can show colour
o = focuses using lenses
E= uses electrons
E= greater resolution due to shorter wavelenght
E= smaller organelles can be see
E= can only view dead specimens
E = no colour
E = focuses using magnets
what is an issue with electron microscopes
production of artefacts ( artifical tissue or structural alteration because of sample prep )
what is the difference between a scanning electron microscope and a transmission electron microscope
SEM = electrons deflected off surface of the object, 3D image, lower resolution, only surface visible
TEM = electrons trasmitted through object, 2D image, higher resolution, detailed internal structures visible
structure and function of the nucleus
function = to store the genetic info to produce protiens
structure = contains chromosomes consisting of protien bound linear DNA and one or more nuclei,
has a nuclear envelope around the outside which is a double membrane, has nuclear pores through the envelope allowing RNA to exit the nucleus, has chromosomes made up chromatin containing the code for protien synthesis, has a nucleolus which prouduces ribosomal RNA and ribosomes
structure and function of the mitochondria
function = site of aerobic respiration, they synthesise ATP
structure = has a double membrane, inner membrane folded into cristae where ATP synthase is embedded, fluid filled region called the matrix, contains its own circular DNA, contains its own smallert ribosomes.
structure and function of ATP
structure = nucleotide made from ribose, adenine, and three phosphate groups
function = hydrolysis of ATP into ADP and Pi is catalysed by ATP hydrolase. This reaction can be coupled to energy requiring reactions in cells. Pi released during ATP hydrolysis can be used to phosphorylate other compounds, making them more reactive.
ATP is resynthesised by condensation of ADP and pi, catalysed by ATP sythase
structure and function ofchloroplasts
function = site of photosynthesis in plants and algae
structure = has a double outer membrane, contains its own circular DNA, contains its own circular ribosomes, fluid filled region called the stroma, contains starch grains to store alpha glucose, made up from stacks of thylakoid membrane called grana that contain the chlorophyll pigments
what is the structure and function of the golgi apparatus
structure = made up from flattened layers of membrane bound sacs called cisernae and associated vesicles
function = recieves substances from the endoplasmic reticulum, process them, then distributes them to their destination.
Modifies and processes triglycerides by combining them with protiens, then packages them for release via exocytosis, forms glycoprotiens by joining sugars to polypeptides, forms vesicles to secrete protiens out of the cell via the cell surface membrane, forms lysosomes.
structure and function of lysosomes
structure = these are small, round membrane bound organelles
function = to release hydrolytic enzymes when they fuse with a vesicle/ phagosome
to remove dead or worn out organelles.
structure and function of ribosomes
structure = made from ribosomal RNA and protiens in the nucleolus, forming two subunits
function = site of translation, part of protien synthesis
structure and function of rough endoplasmic reticulum
structure = flattened sacs of membrane stacked together with ribosomes attached
function = the site of protien sythesis ( specifically any membrane protiens or protiens to be secreted out of the cell )
structure and function of smooth endoplasmic reticulum
structure = flattened sacs of membrane stacked together
function = synthesise lipids such as cholesterol and steriod hormonesand detoxification of toxins
structure and function of the cell wall
structure :
in plants = cellulose
in fungi = chitin
function = to give structural support to the cells, preventing it from changing shape
function of the cell vacuole
stores sap and maintains structural support of the plant cell
when should a logarithmic scales on graphs be used
when there is a large range in number
what is a haemocytometer
helps to standardise counting of cells in an opitcal microscope.
make sure you only count the cells touching the top left lines in order to avoid dealing with parts of cells, avoids counting cells more than once, and allows you to get comparable consistant results.
what are the differences between prokaryotic and eukaryotic cells
- prokarotic are much smaller
- prokaryotic has cytoplasm that lacks membrane bound organelles
- prokaryotic has smaller ribosomes, no nucleus and a cell wall containing murein
- prokaryotic has one or more plasmids
- prokaryotic has a capsule
- prokaryotic has one or more flagella
structure of a virus
- genetic material ( DNA or RNA )
- a capsid
- attachment protiens embedded in a lipid envelope
what happens during cell fractionation
1) homgenise to break open cells
2) filter to remove large cell debris
3 ) suspend in an ice cold isotonic buffer solution
4) place in a centrifuge
what happens in ultracentrifugation
5) centrifuge on slow speed
6 ) first pellet will contain nuclei as it is the densest organelle
7 ) remove supernatant from above the pellet
8 ) centrifuge the supernatent at a faster speed
9 ) mitochondria and chloroplasts will be found in the second pellet as it is less dense
10 ) repeat if required
why does the cell fractionation solution have to be a cold, isotonic buffer solution
- ice cold = stops enzyme activity to prevent digestion of the organelles
- isotonic = same water potential as organelles to prevent osmosis so there will be no osmotic lysis of organelles and no shrinkage
- buffer = maintains pH so that protiens are not denatured.
what is a homologous pair of chromosomes
carry the same genes in the same locus. They could contain different alleles of those genes.
what is mitosis
the part of the cell cycle in which a eukaryotic cell divides to produce two duaghter cells, each with an identical copy of dna produced by the parent cell during DNA replication
5 stages : interphase, prophase, metaphase, anaphase, telophase
mitosis
what is interphase
the chromosomes have replicated
mitosis
what is prophase
chromosmomes coil and condense, they become visible and appear as two sister chromatids joined at the centromere.
nuclear membrane breaks down
mitosis
what is metaphase
chromosomes line up on the equator and attach to the spindle fibres by their centromere
mitosis
what is anaphase
the spindle fibres shorten, the centromere splits, the sister chromatids are seperated and are pulled to opposite poles of the cell ( v shaped )
this requires ATP
mitosis
what is telophase
chromosomes uncoil and become thinner
cytokinesis ( division of cytoplasm ) prodices two new cells
what does binary fission in prokaryotes involve
1) replication of circular DNA and plamsids
2) division of cytoplasm to produce two daughter cells
3) each daughter cell has a single copy of the circular DNA and a variable number of copies of plasmid
how do viruses replicate
- attachment protines attach to receptors in the target cell
- the nucleic acid enters the cell and is replicated
- the cell produces viral protiens and the virus is assembled and released from the cell
how does HIV replicate
- attachment protiens attach to receptors on helper T cells ( its specific target cell )
- RNA enters the cell and reverse transcriptase converts RNA to DNA
- viral protiens, such as those involved in the capsid are produced
- virus particles are assembled and released from the cell
required practical - identify stages of mitosis in plant root tips
1) 5mm onion or garlic root cut off, as this is the region mosy mitosis occurs
2) soaked in hydrochloric acid to break links between cell walls to allow the stain to diffuse into the cell, so they can be more easily squashed
3) a cover slip is then placed om top and pressed firmly onto the sample
4) the cells are firmly squashed to ensure there is a thin layer of clls for light to pass through
5) calculate mitotic index
how can you ensure mitotic index is accurately measured
- examine a large number of fields of view to ensure a representative sample
- repeat the count ensure the figures are correct
how to calculate mitotic index
1) count all cells in mitosis in the field of view
2) divide this by the total number of cells in the field of view
3) repeat many times on fields of view selected at random
what is meiosis
produces daughter cell genetically different from each other.
two nuclear divisions that result in 4 haploid daughter celss from a single diploid parent
- division one = homolgous chromosomes seperate
- divison two = sister chromatids seperate
what are the two processes in meiosis that produces genetic variation in daughter cells
- crossing over between homologous chromosomes = leads to exchange of parts of non sister chromatids between homologous chromosomes which pair up, creating new combos of allels
happens in prophase 1, occurs between non sister chromatids - independant segregation of homologous chromosmes= maternal and paternal chromsomes are reshuffled in any combo, can line up on different sides etc
happens in metaphase 1
how do you calculate the number of different combination of chromosomes following meiosis, without crossing over
2n, where n is the number of homolgous chromosomes pairs ( or haploid numnber )
how do you calculate the number of combinations of chromosomes after the random fertilisation of two gametes
(2 to the power of n) to the power of 2
n is the haploid number and 2 is the number of gametes
what is non disjunction
homologous chromsomes do not seperate iin division one or sister chromatids do no seperate in division 2
this creates a mutation
facts about mitosis
- prodices genetically identical cells
- one nuclear division
- 2 daughter cells produced
- used in asexual reproduction
- used for growth to replace cells to repair damaged tissue
- no crossing over
- no independant segregation
- sister chromatids seperate
- starting cell chromosome number is maintained e.g. haploid to haploid, diploid to diploid
facts about meiosis
- produces genetic variation between the daughter cells
- 2 nuclear divisions
- 4 daughter cells produced
- used in sexual reproduction
- used to produce gametes
- crossing over
- independant segregation takes place
- 1st division= homologous chromosomes seperater
2cnd divison = sister chromatids seperate - chromsome number is halved e.g. diploid to haploid
