cell division: green boxes + forgotten points Flashcards
adaptations of pallisade cells
thin walls to allow diffusion of CO2 .large vacuole to maintain turgor pressure ( hydrostatic pressure)
anaphase
centromeres DIVIDE . Chromatids are SEPERATED and pulled to opposite poles by shortening spindle fibres
4 types of tissue
NEMC nervous, epilethal, muscle, connective
interphase
protein synthesis in G1 energy stores increase + duplicate
cartillage tissue
firm and flexible
digestive system
slamlors small int, large int, anus, mouth, liver, osophagus, rectum, stomach
types of organ systems
digestive system- breaks large insoluble food chunks into small soluble chunks, retians water needed vy body + removes undigestable chunks from body . cardiovascular system - moves blood around body- provide effective transport system gaseous exchange system- brings air into body so that oxygen extracted for respiration and carbon dioxide can be expelled
urinary system
buku bladder, ureter, kidney, urethra
circulatory system
vahc veins, arteries, heart, capillaries
respiratory system
tbbl trachea, bronchi, bronchioles, lungs
what happens if stem cells dont divide fast enough or divide too fast
not fast enough- damaged cells cant be replaced quickly too fast=tumours + cancers form !
what is mitosis ?
division- results in 2 daughter cells having the same number and kind of chromosomes as parent nucleus
source of stem cells
umbilical cords - MULTIPOTENT !
diagram of blood cells
replacement of red and white blood cells
short life span- needs constant replacement , stem colonies in bone marrow produce 3 million erythrocytes to replace these per day
neutrophils live 6 hours, stem cells produce 1.6 billion per kg per hour . figure increases when infection is present !
embryonic stem cells
bone marrow stem cells + umbilical cord
cells present very early on are totipotent. after 7 days, blastocyst forms ( group of cells ) , cells are now in pluripotent state . remain in thi state in fetus until birth
bone marrow cells= multipotent- can be made pluripotent due to growing evidence - advantages of umbilical cord stem cells are that they are in plentiful supply and no invasive surgery is needed. if indivdidual needs needs tissue cultured byt their umbilical cells in the future, body wont reject it !
type 1 diabetes
body destroys its own cells !
use of stem cells - developmental biology
study of changes that occur as multicellular organisms grow and develop from a single cell - eg fertillised egg and why this might go wrong sometimes
prophase (mitosis )
centrioles migrate in pairs to opposite poles
the chromosomes are now tightly coiled and visible as separate bodies under the microscope
the mitotic spindle begins to form at the centrioles
stem cell ethics
law in the UK has changed so that embryos can be created in labs for specific stem cells
-embryo has no rights- life begins at conception - disagreement on who wons the genetic material that is being used for research
controversy holds back development of ways to treat different incurable diseases . umbilical stem cells overcome this but they are only multipotent and not pluripotent , thus resrtricting uefulness . adult stem cells cannot divide that well and could qquire mutations .
research is ongoing on how to turn tissue stem cells into pluripotent stem cells - induced pluripotent adult stem cells (ipsc)
use of plant stem cells dont raise that many ethical concerns
green box: scid
severe combined immuno- defficiency
produces no T cells and without T eclls, B cells dont function either . normally treated w bone marrow transplat - cells differentiate into healthy wbc
aim: remove bone marrow from patients body and gentically modify them so the yfnction properly and produce WBC needed. these are put back into the patient should the condition be corrected
ethical concerns: some childrne developed leukemia - still has potential in the future though
green box: plant cells
leads to unlimited, cheap supply of drugs from plants to be used in medicine
paclitaxel- sued to treat breast cancer - obtained from bark of yew trees- trees have to be mature thus supply is limiteda nd extraction process is difficult and expensive
alternative ways- still difficult and expensive
