2.6 Flashcards
Cytokinesis
Cytoplasmic division following nuclear division resulting in 2 new daughter cells
Interphase
Phase of cell cycle where the cell isn’t dividing, it is subdivided into growth and synthesis phases
Mitosis
Type of nuclear division that produces daughter cells genetically identical to each other and to the parent cells
Chromatids
Replicates of chromosomes
Cytokinesis
Division of the cytoplasm of a cell following mitosis
Mitosis
Type of nuclear division that maintains the chromosome number, each new daughter cell contains same genetic info as parent cell,and they are genetically identical to each other
Haploid
Having only one set of chromosomes represented by ‘n’ symbol
Homologous chromosomes
Matching chromosomes containing the same genes at the same places (loci). They may contain different alleles for some of the genes
Meiosis
Type of nuclear division that results in formation of cells containing half the number of chromosomes if parent cell
Haploid
On set of chromosomes asexual reproduction
Diploid
Two sets of chromosomes sexual reproduction
Gametes
Sex cells
Zygote
Fusion of sperm and egg cells
Allele
Same gene but different variant of the gene
How do cells reproduce
By dividing their contents and then splitting into 2 daughter cells
What could early researchers observing cell division see under light microscope and what couldn’t they
Could easily see behaviour of chromosomes in mitosis which is nuclear division, followed by cytokinesis resulting in 2 daughter cells. But nuclear division and cytokinesis called M phase is only small part of of cell cycle and they couldn’t see the rest
What is between M phase
Interphase
What does interphase look like under a microscope
It appears uneventful
How do scientists now know interphase isn’t uneventful
More sophisticated techniques have enabled scientists to learn that during interphase there are elaborate preparations being made for cell division, in a carefully ordered and controlled sequence with checkpoints
How does cell division cycle divide up
M-division phase, interphase divided into G1 G2 and S and cells may also enter G0 where they undergo differentiation or apoptosis or enter senescence
What are the 2 main checkpoints in cell cycle
G1/S checkpoint aka restriction checkpoint and G2/M checkpoint
What other less important checkpoints are there in cell cycle
One half way through mitosis and in early G1
What is the role of checkpoints
To prevent uncontrolled cell division that would lead to tumours/cancer and to detect and repair damage to DNA
The molecular events that control cell cycle happen in specific sequence so why are checkpoints also important
So cycle can’t be reversed and so DNA only replicated once during each cycle
What is the purpose of the cell cycle
For growth and repair, asexual reproduction and to replace old cells
How does cancer occur in terms of cell cycle
Cells divide uncontrollably, mitosis takes same length of time in cancerous cells but division is uncontrolled so their is a higher proportion of cells dividing in a tissue. Interphase is shorter in proto-oncogens which regulate cell division and growth, proto-oncogens are muted so they don’t undergo cell death as they normally should
What is M phase and what checkpoints are involved
A checkpoint chemical triggers condensation of chromatin. Halfway through cycle, metaphase checkpoint ensures that cell is ready to complete mitosis
What happens to cell in M phase
Cell growth stops, nuclear division(mitosis) occurs, followed by cytokinesis/cytoplasmic division
What is G0 phase and what checkpoints involved
It’s the resting phase triggered during early G1, at restriction checkpoint by a checkpoint chemical. Some cells like epithelial cells lining gut don’t have this phase
What happens to the cell in G0 phase
Cells may undergo apoptosis (programmed cell death), they may undergo differentiation or senescence(no longer divide), some types of cells like neurones remain in this phase for a long time/indefinitely
What is G1 phase and what checkpoints involved
Also called growth phase, a G1 checkpoint controls mechanism and ensures cell is ready to enter S phase and begin DNA synthesis
What happens to cell at G1 phase
Cells grow and increase size(organelles duplicate), transcription of genes to make new RNA occurs, biosynthesis occurs (creates enzymes needed for DNA replication) and p53 tumour suppressor gene helps control this phase
What is S phase and what checkpoints involved
Chromosomes unwind and every molecule of DNA is replicated. There’s a specific sequence to the replication of genes: housekeeping genes (those which are active in all cell types) are duplicated first. Genes that are normally inactive in specific cell types are replicated last
What happens to the cell in S phase
It’s vomited to completing cell cycle in this phase, DNA replicates, when all chromosomes duplicated each one has an identical sister chromatid, phase is rapid as due to exposed DNA base pairs being susceptible to mutagenic agents, it reduces changes of spontaneous mutations happening
What is G2 phase and what checkpoints are involved
Special chemicals ensure cell is ready for mitosis by stimulating proteins that will be involved in making chromosomes condense and in formation of the spindle
What happens to cell in G2 phase
Cell grows
Why do all living organisms need to produce genetically identical daughter cells by mitosis
Asexual reproduction, growth and tissue repair
What is asexual reproduction
Single felled protoctists like amoeba and paramecium divide by mitosis to produce new individuals, some plants like strawberries reproduce asexually by forming new plantlets on end of stolons (runners) and fungi like single cells yeast reproduce asexually by mitosis
Is asexual reproduction rate or common in animals give 2 example
Rater in animals than plants but some female sharks in captivity with no male produce genetically identical daughter sharks and aphids may produce eggs by mitosis
How does mitosis help with growth
All multicellular organisms grow by producing more cells that are genetically identical to each other and their parent cells
How does tissue repair done by mitosis
Wounds heal when growth factors, secreted by platelets and macrophages and damaged cells of blood vessel walls simulate proliferation of endothelial and smooth muscle cells to repair damaged blood vessel
Is mitosis continuous process and what are the 4 main stages
It is a continuous process and 4 stages are prophase, metaphase, anaphase, telophase
What are the events during early prophase
Chromosomes that replicated during S phase and consist of 2 identical sister chromatids now shorten and thicken as DNA supercoils, and nuclear envelope breaks down
What are the events in late prophase
Centriole in animal cells (found in region of cell called centrosome) divide and 2 new daughter centrioles move to opposite poles of the cell. Cytoskeleton protein tubulin threads form a spindle between these centrioles, spindle had 3D structure, similar to longitude lines on globe. In plant cells, tubulin cells formed from cytoplasm
What are the events during metaphase
Pairs of chromatids attach to spindle threads at equator region, they attach by their centromeres
What are the events during anaphase
Centromere of each pair of chromatids split, motor proteins walking along tublin threads pulls each sister chromatid of a pair in opposite directions to opposite poles. As their centromere goes first, the chromatids now called chromosomes assume V shape
What are the events during telophase
Separate chromosomes reach the poles, new nuclear envelope forms round each set of chromosomes. Cell now contains 2 nuclei each genetically identical to each other
What happens once mitosis is complete
Cells split into 2 so each new cell contains a nucleus-cytokinesis
How does cytokinesis work in animal cells
Plasma membrane folds inwards and ‘nips in’ the cytoplasm
How does cytokinesis work in plant cells
An end plate forms where the equator of spindle was and new plasma membrane and cellulose cell wall material are laid down on either side along this end plate
What happens after cytokinesis
2 new daughter cells are now formed, they are genetically identical to each other and to parent cell
What does sexual reproduction increase
Genetic variation
How does sexual reproduction increase genetic variation
It involved combining of genetic material from 2 unrelated individuals of same species by process of fertilisation
What does genetic variation within a population increase
Chances of survival when environment changes as some individuals will have characteristics that enable them to better adapt to the changes
What must body cells be in many organisms for meiosis to occur
Body cells are diploid and they must be haploid gametes for sexual reproduction to occur, so when 2 gamete nuclei fuse during fertilisation, a diploid zygote is produced and Norma chromosome number is maintained through the generations
What does meiosis mean and when does it occur
Means reduction and it occur in diploid germ cells to produce haploid gametes
Where are diploid cells undergoing meiosis found
In specialised organs called gonads-ovaries and testes
What happens before meiosis
Cells are in interphase before meiosis
How many chromosomes in human body
46chromosomes, 23 from mum (egg nucleus), 23 from dad (sperm nucleus)
What are homologous chromosomes
1 maternal and 1 paternal chromosome containing same genes at same places on a chromosome, these matching pairs are homologous chromosomes
Even though homologous chromosomes have same genes what may be different about them
They may contain different alleles of the gene
What happens before meiosis in S phase of interphase
Each chromosome is duplicated as its DNA is replicated l, after which each chromosome consists of 2 sister chromatids (chromosomes pair up in homologous pairs).
How many divisions are in meiosis and how many stages in each division
2 divisions, 4stages in each
What are the stages of meiosis
Prophase 1, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2, telophase 2, cells may enter short interphase before prophase 2
Where does the 2nd stage of meiosis take place
At eighth angle to meiosis 1
What happens after 2nd division in meiosis
Cytokinesis occurs
What are the events during prophase 1 in meiosis
Chromosomes condense and each one supercoils, nuclear envelope breaks down and spindle threads from tubulin protein form from centrioles, chromosomes come together in their homologous pairs, each member of pair consists of 2 chromatids, crossing over may occur
What is crossing over in meiosis
Where non-sister chromatids wrap round each tiger and may swap sections so alleles are shuffled, which creates genetic variation
What are events in metaphase 1 in meiosis
Pairs of homologous chromosomes still in crossed over state, attach along equator of spindle. Each attached to spindle thread by its centromere. Homologous pairs arranged randomly with members of each pair facing opposite poles(independent assortment), way they are lined up in metaphase determines how they will segregate independently when pulled apart in anaphase
What happens in anaphase 1 in meiosis
Members of each pair of homologous chromosomes are pulled apart by motor proteins that drag them along tubulin thread of spindle. Centromeres don’t divide and each chromosome had 2 chromatids, crossed over areas separate from each other resulting in swapped areas of chromosomes and allele shuffling
What are events during telophase 1 in meiosis
In most animal cells 2 new nuclear envelopes form around each set of chromosomes and cell divides by cytokinesis, there is then short interphase when chromosomes uncoil. Each new nucleus contains half original number of chromosomes but each chromosome has 2 chromatids. In plant cells, cell goes straight from anaphase 1 to prophase 2
What happens in prophase 2 in meiosis
If nuclear envelopes reform then they break down, chromosomes coil and condense, each one consisting of 2 chromatids, chromatids of each chromosomes are no longer identical due to crossing over in prophase 1. Spindle forms
What are events in anaphase 2 in meiosis
Centromeres divide, chromatids of each chromosome are pulled apart by motor proteins that drag them along the tubulin threads of spindle, towards opposite poles, chromatids are therefore randomly segregated
What happens during metaphase 2 in meiosis
Chromosomes attach by their centromere to equator of spindle, chromatids of each chromosome are randomly arranged, the way that they are arranged will determine how chromosomes are separated during anaphase
What happens during telophase 2 in meiosis
Nuclear envelopes form around each of the 4 haploid nuclei, in animals the 2 cells now divide to give 4 haploid cells. In plants, a tetrad of 4 haploid cells is formed
What does crossing over do in meiosis and what stage does it happen
Shuffles alleles and occurs in prophase 1
What does independent assortment of chromosomes in anaphase 1 led to
Random distribution of maternal and paternal chromosomes of each pair
What does independent assortment of chromatids in anaphase 2 lead to
Further random distribution of genetic material
What happens after meiosis
Haploid gametes are produced which can undergo random fusion with gametes derived from another organism of same species
In single celled organisms like amoeba how is division of labour determined
By organelles each with specific functions
What does single cell organisms being small mean
Large SA:V ratio so O2 can diffuse across their plasma membrane and waste diffuses out through same membrane
What does multi cellar organisms having small SA:V ratio mean
Most of their cells aren’t in contact with external environment so need specialised cells to carry out their function
How do multicellular eukaryotic organisms start life
As a single undifferentiated cell called a zygote
When does a zygote result
When ovum(egg cell) is fertilised by spermatozoon and 2 haploid nuclei fuse to give a cell with diploid nucleus
Is zygote specialised and what does this mean
Zygote isn’t specialised and all the genes in its genome are able to be expressed (also able to divide by mitosis)
What is a zygote
A stem cell
What happens to zygote after several meiotic divisions
An embryo form containing many undifferentiated embryonic cells
Why do embryonic cells differentiate as certain genes switched off and others expressed more
So that proportions of different organelles differ from those of other cells, shape of cell changes, some contents of cell change
After differentiate what is every cell
Specialised for particular function
In mammals what is an erythrocyte function
Carey oxygen from lungs to respiring cells
In mammals what are neutrophils function
To ingest invading pathogens
How are erythrocytes and neutrophils similar
Very different but both derive from the stem cells in bone marrow
How are erythrocytes adapted to carry out their function
They are small so have large SA:V so oxygen can diffuse across their membrane and reach all regions of cell inside (biconcave shape increases SA:V ratio). They are flexible and have well developed cytoskeleton which allows them to change shape to twist and turn through narrow capillaries, most of organelles lost at differentiation so have no nucleus, mitochondria, ER and little cytoplasm providing space for haemoglobin molecules
How is haemoglobin synthesised
In immature erythrocytes whilst they still have their nucleus, ribosomes and RER
How are neutrophils adapted to their function
They make up 50% of WBC in body, twice the size of erythrocytes and each neutrophil has multi lobed nucleus. They are attracted to and travel towards infection sites by chemotaxis. Their function is to ingest bacteria and fungi by phagocytosis
How are spermatozoa specialised
Many mitochondria to carry out aerobic respiration, ATP provides energy for undulipodium to move cell towards the ovum. Spermatozoa can easily move as they are small, long and thin. Once it reaches ovum enzymes are released from acrosome (specialised lysosomes) and enzymes digest outer protective cover of ovum so sperm head can enter ovum. Head of sperm has a haploid male gametes nucleus and little cytoplasm
How are epithelial cells adapted to their function
Epithelium is lining tissue, found on out and inside of body like alveoli walls and capillaries and lining intestines. Squamous epithelial cells have flattened shape and many epithelial cells have cilia
What are acrosomes
Specialised lysosomes
What is order of plant leaf from cuticle to stomata
Cuticle, upper epidermis, palisade layer, xylem and phloem, spongy mesophyll, lower endodermis, guard cell, stomata
What is lay out of guard cell
Have thickened inner wall, stomata in the middle and chloroplast in the guard cell
Why are palisade cells within leaves well adapted for photosynthesis
They’re long and cylindrical cells, so they pack together closely but with a little space for air to circulate between them and CO2 in these air spaces diffuse into cells, have large vacuole so chloroplasts positioned nearer to periphery of cell which reduces diffusion distance of CO2, they also contain many chloroplasts and contain cytoskeleton threads and motor proteins to move chloroplasts nearer to upper surface of leaf when sun intensity is low and further down when it’s high
Do guard cells contain chloroplasts
Yes
Even through guard cells have chloroplasts why can’t they carry out photosynthesis
They don’t have enzyme needed for 2nd stage of photosynthesis
How are guard cells adapted
Light energy used to make ATP, the ATP actively transports potassium ions from surrounding epidermal cells into guard cells lowering their water potential, water now enters guards cells by osmosis so guard cells swell but at tips cellulose cell wall is more flexible and more rigid when it’s thicker, tips bulge and gaps form between them, stomata enlarged
What happens as stomata open
Sit can enter spaces in layer of cells beneath palisade cells, gaseous exchange occurs and CO2 diffuses to palisade cells as they use it for photosynthesis (maintains steep concentration gradient). Oxygen produced during photosynthesis can diffuse out of palisade cells into air spaces and out through open stomata, when stomata open water vapour lost
What are root hair cells
Epidermal cells on outer layer of young plant roots
How are root hair cells adapted to their function
Hair like projections increase SA for absorption of water and mineral ions, like nitrates, from soil which it projects, mineral ions actively pumped into root hair cell so water potential lowers and water moves in by osmosis down water potential gradient, root hair cells have special carrier proteins in plasma membrane to actively transport mineral in and these cells also produce ATP needed for active transport
What are xylem and phloem
Form vascular tissue of a plant, xylem vessel and phloem sieve tubes are present in vascular bundle
What are cells
Basic building blocks of living organisms
What happens to cells in multicellular organisms and why
Cells become specialised for different functions
What is a tissue
A group of similar cells working together to perform a certain function
What are the human body 4 main types of tissue
Epithelial/lung tissue, connective tissue, muscle tissue, nervous tissue
What is connective tissue
Hold structures together and provide support like blood, bone, cartilage
What is muscle tissue
Made of cells that are specialised to contract and cause movement
What is nervous tissue
Made of cells specialised to conduct electrical impulses
What does epithelial tissue do
Covers and lines free surfaces like skin, cavities of digestive and respiratory system, blood vessels, heart chambers, walls of organs
What are some characteristics of epithelial tissue
Made up almost entirely of cells, each cell is close to each other and form continuous sheet (adjacent cells bound together by lateral contacts like tight junctions and desmosomes),
no blood vessels in epithelial tissue-cells receive nutrients by diffusion from tissue fluid in underlying connective tissue, epithelial tissue either has smooth surface or projections like vili and cilia, have a short cell cycle to constantly replace damaged tissue,
What is epithelial specialised to carry out
It’s function of protection, absorption, filtration, excretion and secretion
Where is connective tissue found in the body
Widely distributed around the body
What does connective tissue consist of
Non-living extracellular matrix containing proteins(collagen and elastin) and polysaccharides like (hyaluronic acid, which traps water)
What is connective tissues function
Separates living cells within tissue and enables it to withstand forces like weight
What are examples of connective tissue (6)
Blood, bone, cartilage, tendons, skin and ligaments
What are immature cells in cartilage called
Chondroblasts
What can chondroblasts do
Divide by mitosis and secrete the extracellular matrix
What happens to chondroblasts once matrix has been synthesised
They become mature and less active chondrocytes maintain the matrix
What are the 3 types of cartilage
Hayline, fibrous, elastic
Where is hayline cartilage found
Forms embryonic skeleton, covers ends of long bones in adults, joins ribs to sternum, found in nose and in the trachea (c-shaped rings keeping it open) and in larynx(voice box)
Where is fibrous cartilage found
In discs between vertebrae in backbone and in knee joints
Where is elastic cartilage found
Makes up outer layer of ear (pinna) and the epiglottis (flap that closes larynx when you swallow
How is muscle tissue specialised
Well vascularised( many blood cells), muscle cells called fibres as they are elongated and contain special organelles called microfilaments made of protein actin and myosin which allow muscle tissue to contract
What is the function of muscle tissue
To allow movement
What are the 3 types of muscle tissue
Skeletal muscle, cardiac muscle, smooth muscle
What is skeletal muscle
Packaged by connective tissue sheets, joined to bones by tendons, they cause bone to move when contracted
What is the cardiac muscle
Makes up walls of heart and allows heart to beat and pump blood
What is smooth muscle
Occurs in walls of intestines, blood vessels, uterus and urinary tract and it propels substances along these tracks
What are the 3 main types of plant tissue
Epidermal, vascular, meristematic tissue
What is epidermal tissue
Equivalent to epithelial tissue in animals, consisting of flattened cells that (apart from guard cells) lack chloroplast and form a protective covering over outer leaves, stems and roots
What do some epidermal cells also have
Walls impregnated with waxy substance forming cuticle, particularly important to plants that live in dry places as it reduces water loss
What is vascular tissue
Concerned with transport-xylem and phloem, both in vascular bundle
What are function of xylem and then phloem
Xylem vessel carry water and minerals from roots all parts of the plant, phloem sieve tubes transfer products of photosynthesis (sucrose) in solution from leaves to parts of the plant the don’t photosynthesis like roots, flowers and growing shoots
What is meristematic tissue
Contains stem cells, from this tissue that all other plant tissues are derived from by cell differentiation
Where is meristematic tissue found
At roots and shoot tips and in cambium of vascular bundle
What are special features of cells in meristematic tissue (meristems)
Have thin walls and little cellulose, don’t have chloroplasts, don’t have large vacuoles, can divide by mitosis and differentiate into other types of cells
What is an example of meristematic tissue
Onion root tips are which is why many of their cells are dividing when viewed under a microscope (mitosis PAG)
What happens as most plant cells mature
They develop a large vacuole and rigid cellulose cell wall which prevents cell from dividing (but plants need to grow and produce new cells, new cells arise at meristems by mitosis)
What do some cambium cells differentiate into
Xylem vessels
What happens to xylem vessel as it mature
Lignin is deposited in their cell walls to reinforce and waterproof them but also kills cells, ends of cell break down so xylem is a continuous column with wide lumen to carry water and dissolved minerals
What do other cambium cells differentiate into
Phloem sieve tubes or companion cells
What happens as sieve tubes and companion cells mature
Sieve tubes lose most of their organelles and sieve plates develop between each cell, companion cells retain their organelles and continue metabolic functions to produce ATP for active loading of sucrose into sieve tubes
What is an organ
Collection of tissues working together to perform same function
What is the organ (leaf) function in a plant
The photosynthesis
What is the organ (root) function in a plant
Anchorage in soil, absorption of mineral ions and water, storage of carbohydrates
What is the organ (stem) function in a plant
Support, holds leaves up so exposed to more sunlight, transport of water and minerals, transport of photosynthesis products, storage of photosynthesis products
What is the organ (flower) function in a plant
Sexual reproduction by meiosis
What are examples of organs in animals (8)
Heart, kidney, liver, brain, optic nerve, bicep muscle, lungs and eyes
What is an organ system
A number of organs working together to carry out overall function of life
What organs/tissues are involved in the organ system (digestive system)
Oesophagus, stomach, intestines and associated glands, liver and pancreas
What life process is carried out by the organ system (the digestive system)
Nutrition to provide ATP and materials for growth and repair
What tissues/organs involved in the organ system (circulatory system)
Heart and blood vessels
What is the life process carried out by the organ system (circulatory system)
Transport to and from cells
What is organ/tissue involved in the organ system (respiratory system)
Airways and lungs, diaphragm and intercostal muscles
What is the life process carried out by organ system (respiratory system)
Breathing and gaseous exchange excretion
What organs/tissues involved in organ system (urinary system)
Kidneys, ureters and bladder
What life process is carried out by organ system (urinary system)
Excretion and osmoregulation
What organs/tissues are involved in integumentary system
Skin, hair and nails
What life process is carried out by the organ system (integumentary system)
Waterproofing, protection and temp regulation
What are organs/tissues involved in organ system, musculoskeletal system
Skeleton and skeletal muscles
What is the life process carried out by the organ system musculoskeletal system
Support, protection and movement
What is the organs/tissues involved in the immune system
Bone marrow, thymus gland, skin, stomach acid and blood
What is the life process carried out by the organ system (immune system)
Protection against pathogens
What is the tissues/organs involved in the organ system (nervous system)
Brain, spinal chord and nerves
What is life process carried out by nervous system
Communication, control and coordination
What organs/tissues involved in endocrine system
Glands that make hormones like thyroid, ovaries, testes and adrenals
What is life process carried out by organ system endocrine system
Communication, control and coordination
What organs/tissues involved in reproductive system
Testes, penis, ovaries, uterus and vagina
What life process is carried out by organ system, reproduction system
Reproduction
What organs/tissues involved in lymph system
Lymph nodes and vessels
What life process is carried out by organ system, lymph system
Transports fluid back to the circulatory system and is also important in resisting infections
What are stem cells
Undifferentiated cells capable of becoming any cell in the organism
What are stem cells described as and why
Pluripotent as they can differentiate into many cell types
What can stem cells do which others can’t
Express all their genes, can divide by mitosis and provide more cells that can then differentiate into specialised cells for growth and tissue repair
What do stem cells characteristics make them important for
Medical research and use
What sources are different stem cells obtained from
Embryonic stem cells, am Oli also chord blood stem cells, adult stem cells, induced pluripotent stem cells
What are embryonic stem cells
Present in early embryo formed when zygote begins to divide
Where are stem cells found in umbilical chord
In umbilical chord blood
What are adult stem cells
Also in kids, are found in developed tissue like blood, brain, muscle, bone, adipose tissue and skin, amounts differentiate cells
What are adult stem cells function
They act as repair system as they are renewing source of undifferentiated cells
What are induced pluripotent stem cells (iPS cells)
They are developed in labs by reprogramming differentiated cells to switch on certain key genes and become undifferentiated
What are stem cells from bone marrow used to treat
Used in bone marrow transplant to treat disease of the blood
What are some blood diseases which can be treated by bone marrow transplant
Sickle-cell anaemia and leukaemia and immune system diseases like severe combined immunodeficiency or SCID
Apart from treating blood diseases what can bone marrow stem cells be used to treat
Can restore patients blood system after treatment for specific cancer types, where patients bone marrow cells can be obtained before treatment, stored and then put back inside patient after treatment
How has stem cells changed drug research
If stem cells can be made to develop into particular types of human tissue, then new drugs can be tested first on these tissues rather than on animal tissue
What are some ways scientists make use of stem cells
To research developmental biology and enable better understanding of how multicellular organisms develop, grow and mature
Why have scientists starting using stem cells to study how stem cells develop
To make certain cell types (blood,bone,muscle,skin) and can learn how each cell type functions and see what hat goes wrong if they’re diseased
What are scientists trying to find out about stem cells
If they can extend capacity that embryos have for growth and tissue repair into later life
Why is stem cell research ongoing
As it’s difficult to culture stem cells in a lab
Why is it hard to culture stem cells in a lab
It’s necessary to find out which cytokine cell signalling molecules are needed to direct the differentiation of stem cells into particular cell types
How have stem cells been used in diabetes treatment
Used to treat mice with type 1 diabetes by programming iPS cells to become pancreatic beta cells and research is underway to develop this treatment in humans for type 1 diabetes
How have stem cells been used to treat liver disease
Bone marrow stem cells can be made to develop into liver cells (hepatocytes) and treat liver disease
How could stem cells treat Alzheimer’s, Parkinson’s or repair spinal chord injuries
Stem cells could be directed to become nerve tissue which could treat these diseases
What is regenerative medicine
Stem cells may be used to populate a bioscaffold of an organ and then directed to develop and grow specific organs for transplanting
How can regenerative medicine mean there is no need for immunosuppressant drugs
If patient cells are obtained and reprogrammed to become iPS cells and used to make a specific organ there will be no need for immunosuppressant drugs
What other conditions may stem cells eventually be able to treat
Arthritis, strokes, burns, vision, hearing loss, duchenne muscular dystrophy and heart disease
Difference between pluripotent and multipotent
Pluripotent can for whole tissue types but not living organisms, multipotent can only form a range of cell types
What is totipotent
Cells can differentiate into any type of cell and produce a whole organism like a zygote (only fertilised egg and first few cells made by early cell division are totipotent)
What are the 3 types of stem cells and where are each found
Totipotent-in fertilised egg,zygote pluripotent-embryo multipotent-adult stem cells, bone marrow
Why does bone marrow need stem cells
Red blood cells don’t have a nucleus so can’t divide by mitosis and therefore need to generate new cells once their cell cycle is finished. Also neutrophils have a limited cell cycle and need bone marrow stem cells to replace them
Where are adult stem cells found
Brain, liver, skin, bone marrow
