Module 2- Cell Division Flashcards
what takes place during G1 phase?
cellular components apart from chromosomes are duplicated,, cell increases in size
what takes place during G2 phase?
second growth phase,, cell continues to increase in size,, energy stores increased,, duplicated DNA checked for errors
what takes place during S phase?
synthesis phase,, DNA replicated in nucleus
what takes place during prophase (mitosis)?
-chromosomes condense becoming shorter and fatter
-nuclear envelope disintegrates
-centrioles move to opposite poles of cell to form spindle fibres
what takes place during metaphase (mitosis)?
chromosomes move to metaphase plate and attach to the spindle fibres by their centromeres
what takes place during anaphase (mitosis)?
-centromere divides separating sister chromatids
-spindle fibres shorten pulling chromatids to opposite poles of the cell by their centromere
what takes place during telophase (mitosis)?
-chromatids reach opposite poles
-two new sets of chromosomes assemble and nuclear envelope reforms around them
-chromosomes uncoil
-cytokinesis begins
what takes place during cytokinesis?
cytoplasm divides and two cells are produced,, begins during telophase
what is a totipotent stem cell?
-can differentiate into any cell including extra-embryonic tissues e.g. placenta
what is multipotent stem cell?
-can only form a range of cells within a certain type of tissue
what is a pluripotent stem cell?
-can form all tissue types but not whole organisms
-origin of different types of tissue within an organism
what are the potential uses of stem cells in developmental biology?
-can be grown into different tissues
to test how effective new medicinal
drugs are and test for side effects/toxicity of them
-studied to see how they develop into different cell types
what happens during crossing over?
chromosomes entangle at the chiasmata resulting in exchange of DNA when they break off and re join during anaphase 1
what happens during independent assortment?
the position of the homologous pair on metaphase plate is random ∴ different combos of alleles face poles leading to genetic variation
how is a erythrocyte specialized for its function?
flattened biconcave shape=increases SA:V maximizing amount of oxygen being transported
no nuclei+not many organelles= more space for haemoglobin
flexible=squeeze through narrow capillaries
how is a neutrophil specialized for its function?
-granular cytoplasm containing many lysosomes (containing hydrolytic enzymes) to attack pathogens
-multilobed nucleus=flexibility=can squeeze through small gaps to get to the site of infections + change shape to engulf (phagocytosis)
how are squamous epithelial cells specialized for their function?
-very thin flattened shape (only one cell thick) providing short diffusion distance for gases e.g. O2 CO2 in alveoli
how are ciliated epithelial cells specialized for their function?
-cells have hair like structures which move in a rhythm to waft mucus containing trapped pathogens away from lungs to the throat///to move egg in fallopian tubes to the uterus
how are sperm cells specialized for their function?
-acrosome contains digestive enzymes which are released to digest the protective layers on the ovum allowing to fertilize
-flagellum tail to enable mobility to swim to egg
-lots of mitochondria to supply energy needed to swim
how are guard cells specialized for their function?
-cell wall is thicker on one side causes, cell to bend / open stomata
how are palisade cells specialized for their function?
-rectangular box shape so can be closely packed to form continuous layer
-thin cell walls to increase rate of diffusion of CO2
-large vacuole to maintain turgor pressure
how are root hair cells specialized for their function?
root hairs increase SA of cell maximizing water+mineral uptake from soil
what are stem cells?
renewing source of undifferentiated cells (unspecialized)
what happens at prophase I?
same as prophase in mitosis ++++
-homologous chromosomes pair up to form bivalents
-crossing over occurs
what happens at prophase II?
-chromosomes that consist of two chromatids condense and become visible again
-nuclear envelope breaks down
-spindle formation begins
what happens at metaphase I?
same as metaphase in mitosis +++
-homologous pairs line up on the metaphase plate
-independent assortment
what happens at metaphase II?
-individual chromatids assemble on metaphase plate
-due to crossing over the chromatids are no longer identical so independent assortment occurs again
what happens at anaphase I?
-homologous chromosomes are pulled to opposite poles of the cell together
-sections of DNA on sister chromatids break off+re-join resulting in exchange of DNA forming recombinant chromatids
what happens at anaphase II?
same as anaphase of mitosis
what happens at telophase I?
-chromatids reach opposite poles
-two new sets of chromosomes assemble and nuclear envelope reforms around them
-chromosomes uncoil
-cytokinesis begins
(same as mitosis)
what happens at telophase II?
-chromatids reach opposite poles
-two new sets of chromosomes assemble and nuclear envelope reforms around them
-chromosomes uncoil
-cytokinesis begins
(same as mitosis)
what happens in mitosis?
the nucleus divides
what is the product of the cell cycle?
two genetically identical daughter cells
what does the G1 checkpoint check for?
DNA damage, cell size, nutrients
what does the G2 checkpoint check for?
correct DNA replication + DNA damage
what does the metaphase checkpoint check for?
if all chromosomes are attached to spindle
when do the checkpoints occur?
at the end of their phases
what happens if the G1 checkpoint fails?
cell enters G0
what happens if the G1 checkpoint is passed?
cell enters S phase for DNA synthesis
what happens if the G2 checkpoint is passed?
mitosis begins
what is mitosis needed for?
-asexual reproduction
-growth and repair of tissues
-production of new stem cells
what is meiosis needed for?
-production of haploid cells
-genetic variation by independent assortment and crossing over
what are the potential uses of stem cells in repair of damaged tissues?
produce new skin for burns on the body
what are the potential uses of stem cells for neurological?
stem cells can be transplanted to areas where needed in order to produce lacked cells causing the disease
what are the ethical issues surrounding stem cell use?
-embryonic stem cells obtained from embryo and then discarded (debate on when life begins)
what are homologous chromosomes?
matching pair of chromosomes, one inherited from each parent which have the same genes but but different alleles of the gene
what stage does crossing over occur?
prophase 1
what stage does independent assortment occur?
metaphase 1 and 2
what is a tissue?
made up if a collection of differentiated cells that have specialized function,, each tissue is adapted for a particular function within an organism
what is an organ?
collection of tissues adapted to perform a particular function within an organism
what is an organ system?
multiple organs working together to carry out a major function in the body e.g. digestive system
what are the four main types of tissue in an organism?
xylem, phloem, muscle, cartilage, squamous and ciliated epithelia
what is cartilage?
firm flexible connective tissue
what is the potency of a stem cell?
its ability to differentiate
where and how are xylem and phloem produced?
produced in meritem by differentiation
where is meristematic tissue found?
-wherever growth is occurring e.g. tips of roots and shoots
-vascular cambium (area sandwiched between phloem and xylem)–can differentiate into the different cells present in xylem + phloem tissues
where are erythrocytes and neutrophils both derived from?
bone marrow
