module 2: cell division Flashcards
what is M phase
checkpoint
what is the G1 checkpoint
checks chemicals needed for replication re present and checks for any damage before s-phase
what is S phase
synthesis- cell replicates DNA
what is G phase 2
cell grows and proteins made for division
what is interphase
cells DNA unravelled and replicated, organelles are replicated and ATP content increases
what is prophase
chromosomes condense, centrioles move to opposite ends of the cell and spindle fibres form, nuclear envelope breaks down
what is metaphase
chromosomes line up on the equator of the cell and attach to spindle fibres
what is anaphase
centromeres divide separating each pair of sister chromatids, spindle fibres contract pulling chromatids to opposite ends of the cell
what is telophase
chromatids reach opposite ends of cell and they uncoil, they are then chromosomes again, nuclear envelopes form around each group of chromosomes so they are now 2 nuclei
what can we use to observe the cell cycle
staining chromosomes
what does meiosis produce
gametes for sexual reproduction, haploid and genetically different
how does genetic variation occur
prophase 1- crossing over of chromatids, alleles are different combo
metaphase 1- lining up of chromosomes is random so daughter cells separate with different combinations of chromosomes
what are stem cells
unspecialised cells that can differentiate into any type of cell
where are stem cells found
early embryos, plant meristem, bone marrow
what are stem cells used for
to replace damaged cells, specialise
what are bone marrow cells used for
differentiate into blood cells
what are meristem cells used for
differentiate into xylem and phloem
what can stem cells cure
parkinsons, alzheimers
what are neutrophils
flexible shape allows them too engulf pathogens, white blood cells, contain digestive enzymes
what are erythrocytes
red blood cells, biconcave shape gives a large surface area, no nucleus so more room for haemoglobin
what are epithelial cells
cover surface of organs, ciliated epithelial have cilia that wafter substances away, squamous are very thin to allow for efficient gas exchange
what are sperm cells
have flagellum so they can swim to egg, have a lot of mitochondria, acrosome has digestive enzymes to break egg surface
what are palisade mesophyll cells
contain chloroplasts, walls are thin for easy diffusion
what are root hair cells
large surface area and thin permeable wall, extra mitochondria for active transport
what are guard cells
pores in surface of leaf for gas exchange, in light they take up water and become turgid, they open stomata
what is cartilage
type of connective tissue in joints, it shapes and supports ears, nose and windpipe
what is xylem tissue
transports water around the plant and supports it, contain dead xylem vessel
what is phloem
transports sugars, arranged in tubes and made up of sieve and companion cells
