B2.3 cell specialisation

Question 1

stem cells

Answer 1

undefferentiated cell that can
divide indefinetly to create more stem cells, no limit to number of times stem cells can divide
or
differentiate (change in gene expression either activate or deactivate gene) to become a specialised cell type in a multicellular organism

Question 2

what are the different catagories for cells

Answer 2

totipotent- can form all cell types
pluripotents- many potentials
multipotent- mutliple potentials
unipotent- only one potential

Question 3

examples of totipotent cels

Answer 3

zygote + morula

Question 4

examples of pluripotent cels

Answer 4

blastocyst + embryo (until 8 weeks pregnant)

Question 5

examples of multipotent cels

Answer 5

foetus (after 8 weeks) + tissue adult stem cells
progenitor cells

Question 6

examples of unipotent cels

Answer 6

terminalyl differentiated cells

Question 7

whats induced ploripotent stem cells

Answer 7

reprogram gene expression of some adult stem cells and make them return into a pluripotent stage

Question 8

explain plants pluripotent stem cells

Answer 8

plant zygote is totipotenet once plant body developed, plants have pluripotent stem cells in regions called meristems, two primary meristems;
-shoot meristem (SAM)
-root meristem (RAM)
responsible for plant longitudinal growth in length, and are located at the tip of stem and roote respectively

Question 9

whats likely source of spare enmbryos

Answer 9

invitrio fertilisation

Question 10

at what step do cells lose thier totipotency

Answer 10

once it becomes a blastocyst (morula -> blastocyst)

Question 11

advantages of using stem cells instead of organ transplant

Answer 11

dont have to wait on donor list , with organ transplant might face rehection, may be cheaper

Question 12

where are hematopoietic stem cells found

Answer 12

they are cells which make blood cells
only found in bone marrow

Question 13

explain how genetically identical cells produced from stem cells can have quite different functions

Answer 13

determined by gene expression, which ones are activated or deactivated

Question 14

how do adult stem cells differn from embryonic stem cells

Answer 14

adult= pluripotent
embryonic= totipotent

Question 15

advantages of using adult stem cells rather than embryonic stem cells

Answer 15

easier to obtain can use patients own stem cells no immunity problem

Question 16

explain hematopoietic cells

Answer 16

they are pluripotent
ca form;
myeloid progenitor cells which form;
phagocytes

or
lymphocytes (lymphoid progenitor cell)

Question 17

what pluripotent cells found in hair follicle

Answer 17

sebaceous gland cells
melanocytes (produce melanin and is a globular protein)
keratinocytes (produces keratine and is a fibrillar protein)

Question 18

what are stem cell niches

Answer 18

locations within tissues where stem cells riside and receive phyiscal and chemical signals that interact and integrate to influence fate of stem cell

sometimes conditions allow stem cells to remain undefferentiated, remain dominant for years
other times when cell specialisation is needed, conditions of stem cell niche allow it to begin differentiate + divide rapidly

Question 19

examples of stem cell niches

Answer 19

hair follicles and bone marrow

Question 20

explain bone marrow

Answer 20

stem cell niche, niche for hematopoietic stem cells (multipotent adult stem cell) forms many human blood cells eg. red blood cells, immune cells, platlets etc.

Question 21

explain hair follicle

Answer 21

its a niche found in bulge region of hair follicles) where hair follicle stem cells reside (multipotent adult stem cell)- give tise to epithelial stem cells eg. melanocytes, keratinocytes

Question 22

cell specialization of stem cells

Answer 22

allows cells to perform a funcion with increase efficiencu
cells can devlop into specific shapes and sizes
cells can create proteins needed to carry out specific metabolic reactions

Question 23

differentiation

Answer 23

development of specialized structures and functions in cells
occurs when different cell types express different genes

Question 24

gene expression

Answer 24

process by which the info encoded in a gene is turned into a function, Often in gene expression, a sequence of DNA (the gene) is transcribed to form RNA which is then translated to form a protein

Question 25

what influences the differentiation of cells during embryonic development

Answer 25

position of a cell within the embryo determines how it differentiates also, gradient/ concentration of the signalling chemical called morphagens impactes gene experession and as a result differenetiation

Question 26

whats a morphogen

Answer 26

signalling molecules direct cell fate decision in a concentration dependent manner controls proliferation, differentiation and petterning during embryonic development to orchestrate formation of tissue and organs

Question 27

explain usage of morphagens

Answer 27

stom cells of the embryo make and secrete morphagens, cells closest to this cell are more exposed to the morphagens receive it in a bigger concentration have a stronger response and differentiate into a specific cell, due to gene activation or deactivation cells further away receive less morphagen and will differentiate into different cells

Question 28

what is the small group of pluripotent cells in a blostocyst from which emrbyoonic stem cell lines are dervied

Answer 28

inner mass cell

Question 29

what is the order is specialized cell size from biggest to smallest

Answer 29

skeletal muscle cell palisade cell human egg cell sperm cell neurone B lymphocyte red blood cell

Question 30

explain the adaptation and reasoning for structure of red blood cells

Answer 30

biconcave disk shaped ells with small width adapted for oxygen transport, small, flexible can fit though narrow capillary vessles the biconcave shape miximises their surface area to volume ration so they can load and unload o2 faster

Question 31

explain the adaptation and reasoning for structure of B lymphocyte (white blood cell)

Answer 31

small when inactive but increase in size during active infection B lymphocytes produce and secrete entibodies (proteins that inactivate pathogens). activation of B lymphocytes curing infection promotes a substantial increase in cell size, due to increase in cells rough endoplasmic reticulum and golgi which are used to make and secrete antibody protein

Question 32

explain the adaptation and reasoning for structure of motor neurone

Answer 32

large cell body with long narrow axon they send info from CNS to muscles and glands. Axons are longest part of body allows for rapid transmission of info along the distacne, large cell body containg many organelles for the synthesis of proteins needed to transmit electrical impulses and of neurotransmitters to signal receiving cells

Question 33

explain the adaptation and reasoning for structure of sperm cell

Answer 33

long narrow strong flagellum for propulsion deliver DNA to an egg during sexual reproduction , adpated to reduce resistence as cell moves towards egg Dna in nucleus extremelly tightly packed, volume minimized for transport. Cell very narrow because does not contain organelles contain many mitochondria placed where they can most efficiently power flagellum, flagellum tial propels the sperm to egg, helps it burrow through egg coat

Question 34

explain the adaptation and reasoning for structure of human egg cell

Answer 34

large and spherical as largest largest of any human cells, eggs store all the materials and nutritional reserves needed for initial development of the embryo, large cells result of unequal division of cytoplasm during cytokinesis

Question 35

explain the adaptation and reasoning for structure of striated muscle fibre cell

Answer 35

long narrow and cylindrical shaped cells primary function of striated muscles is to generate force and contract in order to cause movement, the long narrow dimensions of the cells allow for a greater length

Question 36

explain the adaptation and reasoning for structure of cerebellum neuron cell

Answer 36

cell body very small with long narrow axons that can be extended cerebellum primarily responsible for muscle control including balance and movement. The cerebellar granule cells are most numerous neurones of brain. They are interneurones that function in integrations of sensory info and motor activity. They are also among smallest neurones, the very small volume of these neurones allows brain to densely pack

Question 37

property of totipotent stem cell

Answer 37

capable of giving rise to any cell type in an organism

Question 38

if cells of a multicellular organism have same genes how can there be many different cell types in a body

Answer 38

some genes but not others are expressed in each cell type