M2 chapter 6- cell divison Flashcards
why do we need new cells?
growth and repair
what are the stages of mitosis?
prophase
metaphase
anaphase
telophases
(interphase and cytokinesis aren’t technically part of mitosis)
what is the m phase of cell division?
mitosis and cytokinesis
what 3 stages is interphase in?
G1,s, G2
how is the cell cycle regulated?
checkpoints that occur at key points to ensure the process is okay to continue
what happens in interphase?
cell gets ready to divide
cells dna is unravelled and replicated
organelles are also replicated
atp content is also increased
what is misosis?
1 cell divided to become 2 cells
some organisms use this to reproduce asexually
is a continuous process
what are the structure of chromosomes in mitosis?
made of 2 strands joined in middle by centromere
separate strands are chromatids
has 2 strands because each chromosome has an identical copy of itself during interphase
how are the chromosomes arranged after mitosis?
when mitosis is over chromatids and up as 1 single strand in new cells
what happens in prophase?
chromosomes condense
centrioles move to ends of cells to create spindle fibres
nuclear envelope breaks down
chromosomes are free in the cytoplasm
what happens in metaphase?
chromosomes line up along equator of cell
they attached to the spindle by centromere
at this checkpoint cell checks all chromosomes are attached to spindle before it continues
what happens in anaphase?
centromeres move apart separating each pair of sister chromatids
spindles contract pulling chromatids to opposite ends of cell
what happens in cytokinesis?
cytoplasm divides and cleavage furrow forms to divide the cells, creating 2 identical daughter cells.
this process begins in anaphase and ends in telophase
what happens in telophase?
chromatids reach opposite poles and uncoil to become chromosomes. the nuclear envelope then forms
what is different about cytokinesis in plants compared to animals?
it is initiated by the formation of a cell plate in the middle of the cell.
how would you observe mitosis scientifically?
treat tips of roots in HCL and break them open then spread a few on a slide and view them under a microscope. because the roots are part of a plant that keeps on growing
what are sperm and egg cells?
gametes
what is a cell with 2 of each chromosome called?
diploid
how is genetic differentiation created?
chromosomes that make up each pair are the same size and have same genes however could have different versions of genes aka alleles
what are gametes?
haploid cells
what is meiosis for?
cell division to produce gametes which are all genetically different
what happens in interphase in meiosis?
dna unravels and replicates to produce double armed chromosomes, sister chromatids
how many divisions happens in meiosis?
2- meiosis 1 and meiosis 2
what happens in meiosis 1?
the chromosomes number halves
what happens in meiosis 2?
daughter cells from meiosis 1 undergo prophase, metaphase, anaphase, telophase again and cytokinesis so now the 4 cells produced have a diploid no of chromosomes.
when does crossing over occur?
prophase
what is crossing over?
in meiosis 1 homologous pairs of chromosomes come together and pair up. the chromatids then twist around each other and alleles can be swapped from one chromatid to another, this means the daughter cells in meiosis 2 contained chromatids with different alleles
what are stem cells?
unspecialised cells that can develop into different types of cells. all multicellular cells have these
what is differentiation?
when stem cells divide to become new cells which are then specialised cells.
what can stem cells also divide into?
can also divide in to undifferentiated stem cells (replicate)
what are stem cells in animals for?
used to replace damaged cells for example red and white blood cells
what are stem cells in plants for?
used to make new shoots and roots. stem cells can differentiate into various types of plant tissue.
where are stem cells found in plants?
meristem, can become xylem or phloem cells
what can stem cells be used to treat in medicine?
heart disease by making replacement heart cells
Alzheimer’s by regrowing healthy nerve cells as they die in this condition
Parkinson’s by regenerating dopamine neurons
what are specialised cells?
when cells differentiate into cells with a specific function, with a structure adapted to this
what are erythrocytes?
red blood cells
what are neutrophils?
white blood cells
how are erythrocytes specialised?
carry oxygen in the blood
bio concave shape
no nucleus so there is m ore room for haemoglobin
how are neutrophils specialised?
defends body against disease
flexible shape to engulf pathogens
contains lysosomes in the cytoplasm to break down pathogens
how are epithelial cells specialised?
cover surface of organs
cells joined by interlinking cell membranes
what are some examples of epithelial cells?
ciliated epithelial cells- in trachea to move pathogens put of airway
microvilli- found in small intestine to increase SA
squamous epithelial cells- allows gas exchange
how are sperm cells specialized?
acrosome- contains digestive enzyme in head to enable penetration
many mitochondria to provide energy to swim
flagella helps it swim to the egg cell
what are palisade mesophyll cells?
where photosynthesis occurs in plants
how are palisade mesophyll cells specialized?
lots of chloroplasts to absorb sunlight
thin walls so CO2 can diffuse into the cells
what are root hair cells?
cells found in the root of plants that absorb water and mineral ions to give to the plant
how are root hair cells specialized?
larger SA for efficient absorption
thin permeable cell wall to allow diffusion to occur quicker
cytoplasm contains extra mitochondria so active transport of ions can occur
how are guard cells specialized?
In light, guard cells take up water and become turgid.
Thin outer walls and thick inner walls, force them to bend outwards, opening the stomata, allowing for gas exchange for photosynthesis.
what is a tissue?
group of cells that are specialised to work together to carry out a certain function
what is squamous epithelial tissue?
single layer of flat cells lining a surface found in alveoli in lungs providing a thin exchange surface for gas exchange
what is cilliated epithelial tissue?
layer of cells covered in cilia
found on surfaces where things need to be moved eg; the trachea
what is muscle tissue?
bundles of elongated cells called muscle fibres. 3 different types
smooth- lining of stomach
cardiac- found in heart
skeletal- used to move
what is cartilage tissue?
connective tissue found in the joints. it shaped and supported ear,nose and windpipe. formed when chondroplasts secrete an extra cellular matrix which they become trapped inside
what is xylem tissue?
transports water around the plant and supports it. made up of dead and living parenchyma cells
what is phloem tissue?
transports sugar around plants. arranged in tubes made up of sieve tube elements, companion cells and ordinary cells. each sieve wall has holes in so sap can move
what are organs?
group of different tissues that work toghter to perform a certain function.
for example lungs carry out gas exchange and contains squamous and celibates epithelial tissue
what organ is found in plants?
leaf- carries out gas exchange and contains palisade tissue, epidermal tissue and xylem and phloem tissue
what is an organ system?
when organs work together. for example the circulatory system contains heart, veins, arteries, capillaries ect
