Cell Cycle, Mitosis & Meiosis Flashcards
cytokinesis
cytoplasmic division following nuclear division resulting in 2 new daughter cells
interphase
phase of cell cycle where the cell is not dividing; it is subdivided into growth and synthesis phases
mitosis
type of nuclear division that produces daughter cells genetically identical to each other and the parent cell
chromatids
replicates of chromosomes
haploid
having only 1 set of chromosomes
homologous chromosomes
matching chromosomes containing the same genes at the same places (loci)- may contain different alleles
meiosis
type of nuclear division that results in the formation of cells containing half the number of chromosomes of the parent cell
differentiation
process by which stem cells become specialised into different types of cell
epithelial cells
cells that constitute lining tissue
erythrocyte
red blood cell
neutrophil
type of white blood cell that is phagocytic
stem cell
unspecialised cell able to express all its genes and divide by mitosis
genome
genetic material within an individual
gene pool
all the genetic material within a population
guard cells
in leaf epidermis, cells that surround stomata
palisade cells
closely-packed photosynthetic cells within leaves
root-hair cells
epidermal cells of young roots with long hair-like projections
tissues
group of cells that work together to perform a specific function
meristem
area of unspecialised cells within a plant that can divide and differentiate into other cell types
organ
collection of tissues working together to perform a function
phloem
tissue that carries products of photosynthesis in solution within plants
xylem
tissues that carries water and mineral ions from the roots to all parts of the plant
organ system
a number of organs working together to carry out an overall life function
why do cells divide
for growth and repair
which cells undergo division in the body and when
skin cells- replacement and repair
epithelial cells- mouth and lining of stomach
purpose of controlled sequence of cell division with checkpoints
prevent uncontrolled division leading to tumours
detect and repair damage to DNA
ensure DNA isn’t reversed and only replicated once
5 phases of the cell cycle
M phase G0 phase G1 phase S phase G2 phase
function of mitosis (M phase)
asexual reproduction, growth, tissue repair
structure of chromosomes
made of DNA, protein and small amount of RNA, very large molecule, coiled, 4 chromatids and 1 centromere
types of protein involved
histone
scaffold
polymerases
histone proteins
large number of positive amino acids that bind to phosphate group of DNA so stabilise structure
polymerases
enzyme transcription + DNA replication prior to divisions of chromosomes
process of cytokinesis
after mitosis, cell splits into 2 and each new cell contains a nucleus
animal cells in cytokinesis
cytoplasm ‘nips in’ due to membrane folding inwards
plant cells in cytokinesis
end plate forms where spindle equator of the cell was situated, new cellulose and membrane are laid down along the cell plate
number of divisions in meiosis
2
stages in divisions of meiosis
prophase, metaphase, anaphase, telophase
fusion of the nuclei of gametes form
a zygote
a diploid zygote is formed by
fertilisation
gametes are produced in
the ovaries or testes
phases of interphase
G1, S, G2
why is the synthesis phase rapid
exposed DNA base pairs are more susceptible to mutagenic agents so reduces chances of spontaneous mutations
what is tubulin
a cytoskeleton protein
structure of the spindle
3D structure
lines of latitude on a globe
in plant cells they form from cytoplasm
why are chromatids of each chromosome no longer identical in prophase 2
crossing over in prophase 1
4 main tissues in animal body
epithelial
connective tissues
muscle tissues
nervous tissues
epithelial
lining tissue
connective tissues
hold structures together & provide support e.g. blood,bone,cartilage
muscle tissues
made of cells that are specialised to contract & cause movement
nervous tissues
made of cells specialised to conduct electrical impulses
pluripotent
refer to stem cells- capable of giving rise to several different cell types
examples of differentiating cells in animals
erythrocytes
neutrophils
from stem cells in bone marrow
examples of differentiating cells in plants
xylem tissue
phloem tissue from meristem cells (like cambium)