Cell division (paper 2) TOPIC 1 & 6 Flashcards
.what do most cells in the human body contain
a nucleus
what does a nucleus contain
the genetic meterial of the cell
what is the genetic chemical in the nucleus called
DNA
what is DNA arranged into
structures call chromosomes
what is a chromosome
a coiled molecule of DNA carrying different genes
what is a the term for a body cell
somatic cell
how are chromosomes found in somatic cells
in pairs
why are chromosomes found in pairs
because each pair is inherited from the person’s mother and one from their father
how many chromosomes do humans contain
46 chromosomes in 23 pairs
what is the haploid number and what is it for a human
the number of pairs of chromosomes
23 pairs in a human
what is the diploid number and what is it for humans
the number of chromosoms in a cell
46 chromosomes
what are gametes
sex cells
what is the female sex cell
an ovum
what is the male sex cell
sperm
what is the word for the picture of chromosomes when removed from a nucleus and arranged in order
a karyogram or karyotype
what are karyograms/karyotypes used for
to determine the sex of an individual and diagnose genetic disorders
how can you tell if an individual is female
they will have 2 x chromosomes
how can you tell if an individual is male
they will have one x chromosome and one y chromosome
how are new cells made
by the proccess mitosis
define mitosis
the growth and repair of tissues
what is the cell cycle
the series of stages which somatic cells divide in
what happens in stage one of the cell cycle for mitosis (interphase)
- cell increases in size
- the DNA is replicated
- the number of organelles is doubled
what happens in the second stage of the cell cycle for mitosis (prophase)
- the chromosomes condense in the middle of the cell
- half the chromosomes are pulled to one pole of the cell
- two nuclei are formed
- cell is split to form 2 genetically identical daughter cells
what is the longest stage of mitosis
when the cell grows and replicated their DNA and increases the sub-cellular structures (the first stage)
what do genes do
they carry the instructions to control a characteristic
what is binary fission
the method of asexual reproduction which single-cell organisms use to create a copy of themselves
in binary fission are plasmids equally shared between the daughter cells? explain?
No - the plasmids are shared randomly, but one loop of DNA goes to one daughter cell and the other to the other daughter cell
what happens in the process of binary fission
- Cell replicates DNA
- cell grows
- cell wall forms and cell membrane invaginates
- daughter cells formed
what type of cells conduct binary fission
prokaryotic
what is meiosis used for
the formation of gametes
what is similar in the processes mitosis and meiosis
DNA is duplicated before cell division in both
mitosis? meiosis?
which produces genetically identicel cells and which produces genetically unique cells
genetically identicle cells - mitosis
genetically unique cells - meiosis
mitosis? meiosis?
results in haploid cells or diploid cells
diploid = mitosis
haploid = meiosis
mitosis? meiosis?
occurs only at certian times of life cycle or takes place throughout lifetime
occurs throughout lifetime = mitosis
occurs at certain times of lifecycle = meiosis
mitosis? meiosis?
involved in asexual or sexual reproducution
asexulal reproduction = mitosis
sexual reproduction = meiosis
what is a stem cell
an undifferentiated cell
what is the function of a stem cell
they can differentiate to become different types of specialised cells
what are the three different types of stem cells
- embryonic
- adult
- plant
what is different for stem cells in animals comapred to plants
in animals little to no growth takes place, the same type of cells are made. in plants they are able to differentiate trhoguhtout their lives (known as meristem cells)
what is the name given to the stem cells in plants which are undifferentated
meristem cells
how are embryonic stell cells formed
after a sperm cell and egg fuse to form a zygote, that cell divides to form an embryo.
the inner cells of this ball are embryonic stem cells
give an example of an adult stem cell
bone marrow
what are adult stem cells described as
multipotent stem cells
what are embryonic stem cells described as
totipotent stem cells
where are the meristem cells found in plants
at the tips of roots and shoots
what are the ethical againsts and fors in stem cell research
+they are treating and curing patients
+wasted embryos from fertilisation are being used
-they think its a potential life
-embryos cannot consent
-think time and money should be used to find an alternative solution
what are the two types of reproduction
- asexual
- sexual
evalutate asexual reproduction
- involves mitosis (or buimary fission in bacteria)
- involves only one patient
- does not involve fusion of gametes
- does not result in mixing genetic info
- produces genetical identical offspring
how can plants reproduce asexually
using the process vegetative reproduction
what type of production is in animalas
sexual
define sexual reproduction
the mixing of genetic information which leads to variety in the offspring - the offspring are genetically different to both parents
what are the male gametes called
sperm
what are the female gametes called
ova
which cell division process does the formation of the gametes involve
meiosis
how many chromosomes does each gamete contain
the haploid number of chromosomes (half)
describe fertilisation
- the ovum and sperm fuse together
- results in single zygote cell (has full number of chromosmes)
- zygote develops into the embryo
what type of plants does sexual reproduction occur in
flowering plants
what is the reproductive organ of any flowering plant
the flower
what is the male gamete in plants
the stamen (anther and filament) which contain the pollen
what is the female gamete in plants
the carple (stigma, style and ovary) which contains the ocules
what happens during pollination
the pollen is transferred from the anther to the stigma
what happens when a cell divides to form gametes
- copies of the genetic info is made
- cell divides twice to form 4 gametes
- each have a haploid number of chromosomes
- all gametes are genetically different from each other
whtat are the advantages of sexual reproduction
- genetically varied = survival advantage if change occurs
- natural selection sped up by selective breeding
what are the advantages of asexual reproduction
- only one parent needed
- more time and energy efficient
give some examples of organisms that use BOTH sexual and asexual reproduction
- malaria parasite (protist)
- fungi
- strawberry plant
- daffodils
how does the malaria parasite reproduce
sexually - when inside the mosquito
asexually - when inside the human
how does fungi reproduce
sexually - releases spores sexually
asexually - releases spores asexually
how does the strawberry plant reproduce
sexually - produces gametes in flowers
asexually - produce runners
Describe mitosis
Cell increases in size and dna replicates
One set of chromosomes get pulled to each pole of the cell
Cell membrane and cytoplasm divide into genetically identical cells