Organisation and Specialisation of cells Flashcards
cell
the basic unit of life
multicellular
an organism which has more than 1 cell
specialised
having a particular structure to carry out a specific function
level of organisation
specialised cells -
tissues -
organ -
organ systems -
whole organism
differentiated
where cells become specialised to carry out a specific function
erythrocytes
red blood cell
how are erythrocytes specialised
- flattened biconcave shape
- no nuclei, few organelles
- flexible
how is having a flattened biconcave shape suited to an erythrocytes function
- increases their SA:V ratio
- allows them to transport maximum oxygen around the body
how does not having a nuclei or many organelles suited to an erythrocytes function
- increases space for haemoglobin, the molecule that carries oxygen
how is being flexible suited to an erythrocytes function
- they can squeeze through narrow capillaries
neutrophils
type of white blood cell
what do neutrophils do
play an important role in the immune system
how are neutrophils specialised
- multi lobed nucleus
- granular cytoplasm
how does a multi lobed nucleus help neutrophils with their function
makes it easier for them to squeeze through small gaps to get to the site of infections
how does the granular cytoplasm help neutrophils with their function
it contains many lysosomes which contain enzymes used to attack pathogens
sperm cells
male gametes
sperm cell function
deliver genetic information to the female gamete (ovum)
how is a sperm cell specialised
flagella
mitochondria
acrosome with digestive enzymes
how does the flagella help the sperm cell
for movement
how does the sperm cell having lots of mitochondria useful
it supplies the cell with energy needed to swim
how is the acrosome containing digestive enzymes useful for the sperm cell
- they are released to help digest the outer protective layers around the ovum to allow the sperm cell to penetrate, causing fertilisation
where are palisade cells found
mesophyll
how are palisade cells adapted
- contain chloroplasts
- rectangular box shapes
- thin cell walls
- large vacuole
- chloroplasts can move
how does the palisade cell having chloroplasts make it suited to its job
- chloroplasts absorb light for photosynthesis
how does the palisade cell being in rectangular box shapes make it suited to its job
- they can be closely packed together to form a continuous layer
how does the palisade cell having thin cell walls make it suited to its job
- rate of diffusion of carbon dioxide increases
how does the palisade cell having a large vacuole make it suited to its job
- to help maintain turgor pressure
how do the chloroplasts being able to move make the palisade cell suited to its job
- they can move in the cytoplasm to absorb more light
where are root hair cells found
at the surfaces of roots near the growing tips
how are root hair cells specialised
- long extensions
how do root hair cells having long extensions allow them to carry out their function better
it increases the SA of the cell
this maximises the uptake of water and minerals from the soil
what are guard cells
cells which form small openings called stomata
where are guard cells found
surface of leaves
function of guard cells
allow diffusion of gases for photosynthesis
how are guard cells adapted for when they lose water
- they become less swollen
- they change shape due to osmotic forces
- the stoma closes to prevent further water loss
why do guard cells have 1 thicker cell wall
so the cell won’t change shape symmetrically as its volume changes
tissue
made up of a collection of differentiated cells which have specialised function/s
main tissues in animals
nervous tissue
epithelial tissue
muscle tissue
connective tissue
what cells is the squamous epithelium made of
squamous epithelial cells
why is the squamous epithelium tissue so thin ?
- the squat cells which make it up
- one cell thick
what is the squamous epithelium tissue used for
rapid diffusion across surfaces
give characteristics of the squamous epithelium tissue which makes it suited to its function
thin
give an example as to where the squamous epithelium tissue can be found
lining of lungs
what is the ciliated epithelium made up of
ciliated epithelial cells
describe structure of ciliated epithelium
- has cells with hair like structures called cilia which move in a rhythmic manner
give an example as to where ciliated epithelium is found
lining of trachea, allowing mucus to be swept away from lungs
what type of tissue is cartilage
connective
where is cartilage found
outer ear
nose
at the ends of bones
what fibres to cartilage contain
elastin
collagen
describe structure of cartilage
firm, flexible CT
composed of chondrocyte cells embedded in an extracellular matrix
give a function of cartilage
prevents ends of bones from rubbing together and causing damage
function of muscle
needs to shorten in length to move bones, which move the body
MOVEMENT
name a type of muscle fibre
skeletal muscle fibres
(muscles which are attached to bone)
what do skeletal muscle fibres contain
myofibrils that contain contractile proteins
in pictures what are the myofibrils (muscle fibres)
pink bands
in pictures of muscle tissue where is connective tissue
thin white strips
name plant tissues
- epidermis tissue
- vascular tissue
epidermis tissue
covers plant surfaces
vascular tissue
transports water and nutrients
nervous tissue
supports transmission of electrical impulses
epithelial tissue
covers body surfaces, both internal and external
muscle tissue
contraction
connective tissue
holds other tissues together or for transport medium
epidermis
single layer of closely packed cells covering the surfaces of plants
what is the epidermis often covered by
waxy, waterproof cuticle
stomata
why is the epidermis covered by waxy cuticle
to prevent water loss
what do stomata do on the epidermis
allow CO2, O2, and water vapour in and out
what type of tissue is the xylem and phloem
vascular
xylem function
transport water and minerals throughout plants
structure of xylem
- vessel elements that are elongated dead cells
how is the xylem given extra strength and support
- the walls are strengthened by waterproof material lignin
phloem function
transports organic nutrients, particularly sucrose from leaves and stems where it is made by photosynthesis to all parts of the plant
phloem structure
composed of columns of elongated sieve tubes cells separated by perforated walls called sieve plates
organ
collection of tissues that are adapted to perform a function in an organism
give an example of an organ
heart
heart function
pumps blood around body
what is the heart made up of
muscular tissue
connective tissue
example of a plant organ
leaf
leaf function
photosynthesis
what is a leaf made up of
epidermis tissue
vascular tissue
organ system
organs work together to carry out a major function in the body
organ system examples
digestive system
cardiovascular system
gaseous exchange system
digestive system
- takes in food, breaking down large insoluble molecules into small soluble ones
- absorbs nutrients into blood
- retains water needed by body
- removes any undigested material
cardiovascular system
- moves blood around body
- provides effective transport system for the substances it carries
gaseous exchange system
- brings air into body
- extracts oxygen for respiration
- removes carbon dioxide
how is differentiation linked to genes
- it involves cells being able to express some genes but not others in the cells genome
what kind of cells do all plant and animal cells begin as
undifferentiated cells
what are undifferentiated cells
cells which are not adapted to any particular function and have the potential to become any one of the range of specialised cell types
what are stem cells
undifferentiated cells which have the potential to become any one of the range of specialised cell types
what are stem cells able to do
- undergo cell division again and again
- they are the source of new cells necessary for growth and development and tissue repair
once stem cells become specialised, what do they lose their ability to do
- divide, so they enter the G0 phase
why do the activity of stem cells have to be strictly controlled
- if they don’t divide quick enough, tissues aren’t efficiently replaced, leading to ageing
- if they divide too fast, they form masses called tumours, which could lead to cancer
potency
a stem cells ability to differentiate into different cell types
totipotent
stem cell which can differentiate into any type of cell and can produce a whole organism
give examples of totipotent stem cells
fertilised egg / zygote
8-16 cells from its first few miotic divisions
pluripotent
stem cells can form all tissue types but not whole organisms - they are the origin of different tissue types within an organism
give an example of a pluripotent stem cell
early embryo cells
multipotent
can only form a range of cells within a certain type of tissue
give an example of a multipotent cell
haematopoietic stem cells in bone marrow give rise to different types of blood cell
when cells differentiate what happens
they become adapted to their specific role
what is the adaptation that the specialised cell has had dependant on
the function of the tissue, organ, and organ system to which the cell belongs
where are all blood cells derived from stem cells
bone marrow
what is the function of mammalian erythrocytes
transport oxygen around the body
what is the lifespan of eyrthrocytes
120 days
why do erythrocytes have short life spans
they have no nuclei and organelles
how many erythrocytes do the stem cell colonies in the bone marrow produce daily
3 billion per kg of body mass
how long do neutrophils last for
6 hours
how many neutrophils do the colonies of stem cells in bone marrow produce per hour
1.6 billion per kg of body mass
what are the sources of animal stem cells
- embryonic stem cells (totipotent)
- tissue/adult stem cells (e.g bone marrow) (multipotent)
- umbilical cords of newborn babies
why are stem cells found in umbilical cords good
- plentiful supply
- no invasive surgery needed
-wouldn’t be rejected in a transplant to the umbilical cords owner
where are plant stem cells found
meristematic tissue
where is meristem found
wherever growth is occuring in plants
between phloem and xylem tissue
vascular cambium
meristem which is located between phloem and xylem
what can meristematic tissue found at the vascular cambium differentiate into
different cells present in the phloem and xylem tissues
what kind of stem cell is a meristem
pluripotent
potential uses of stem cells
- heart disease
- type 1 diabetes
-parkinsons disease - alzheimers disease
- macular degeneration
- birth defects
- spinal injuries
what are stem cells already used for
- treatment of burns
- drug trials
- developmental biology
why are people against the use of stem cells
- destruction of embryos
- religious objections
- life begins at conception belief and so destruction of embryos is murder
umbilical cords which are multipotent, overcomes the use of embryonic stem cells to an extent, but why not fully ?
because they aren’t pluripotent, so their usefulness is restricted
what are induced pluripotent stem cells
adult stem cells which have been genetically modified to act like embryonic stem cells and so are pluripotent
