B2 - cell division Flashcards
what do chromosomes do
carry the genes that contain instructions for making new cells and tissues and organs
what does a gene do
controls a characteristic or part of a characteristic. it’s a section of dna
what does mitosis do
produces the addition cells needed for growth and development in multicellular organisms
describe the cell cycle
stage 1: cells grow bigger, increase their mass, carry out normal cell activities, replicate DNA to form two copies of each chromosome, increase number of subcellular structures
stage 2: mitosis: one set of chromosomes is pulled to each end of cell and the nucleus divides
stage 3: cytoplasms sh cell membranes divide to form two identical daughter cells
why do we show signs of aging
mitosis slows down so new cells are not being produced as quickly
what is an unspecialised cell called
stem cell
why do we specialise cells
to carry out particular functions
why do adult stem cells replace dead or damaged cells
because some differentiated cells (like red blood cells and skin cells) cannot divide at all
when do most animal cells differentiate
very early in life
when do plant cells differentiate
they retain the ability to throughout their lives
where are undifferentiated cells formed in plants and animals
plants - meristems
animals - bone marrow and embryo
how do you clone a plant
by taking a cutting
how can stem cells be used in medicine
spinal injuries - inject nerve cells grown from embryonic stem cells into spinal cords of paralysed human patients
diabetes - scientists are using stem cells to grow blood sugar sensitive cells and produce the hormone insulin
how can stem cells be used in plants
saving rare plants by cloning them
producing large numbers of plants (like orchids) to sell
produce large numbers of identical crop plants that many be disease resistant
why do some people disagree with the use of embryonic stem cells
embryo cannot consent - violation or human rights
religious beliefs - cannot accept interference with human reproduction
difficult, expensive, hard to control, slow
may cause cancer - embryonic stem cells divide rapidly
