B13 Flashcards
what are the 2 types of reproduction
sexual and asexual
characteristics of sexual reproduction
- 2 parents are needed
- offspring will have genetic variation
- fusion of gametes
characteristics of asexual reproduction
- 1 parent is needed
- offspring will be genetically identical to one another (clones)
advantages of asexual reproduction
- enables an organism to populate a new habitat quickly
- make sures successful characteristics are passed on
- faster than sexual reproduction
disadvantages of asexual reproduction
- no genetic variation so all organisms have the same weakness
- no genetic variation means it is difficult to adapt to the environment
advantages of sexual reproduction
- genetic variation in offspring
- natural selection can be manipulated by humans to have a better yield
what is meiosis
cell division of gametes only
where does meiosis take place
in the reproductive organs
how does meiosis work
- a gamete makes clones of chromosomes so it’ll have 92 chromosomes (46 pairs)
- similar pairs of chromosomes match up
- genes get swapped in the chromosome
- cell divides twice and then twice again
is a gamete a haploid or diploid
haploid
are gametes similar to each other
no they are not. each gamete is genetically different from one another
what is the point of meiosis
- for making egg and sperm cells
what are the male and female gametes of flowers
male - pollen
female - ovule
how do flowers undergo sexual reproduction
the pollen of a flower pollinates another ovule creating a seed
how do fungi reproduce
mostly asexually but at times sexually to
how do fungi create gametes and what is the name of said gamete
spores are made by mitosis
how does a fungi reproduce asexually
- spores are made by mitosis and are stores in fruiting bodies
- spores then become mycelium
- mycelium grown into the fungi
how do fungi reproduce sexually
- 2 cells with different chromosomes mix to form a diploid cell
- meiosis occurs to form diploid spores
- the spores then form mycelium which grow into the fungi
how do malaria in a mosquito reproduce
sexually in a human but asexually in a mosquito
how do some plants grow by runner
a new, clone plant forms at the end of a runner by mitosis in asexual reproduction
the steps of reproduction of malaria
- the parasite goes into the liver of a human where it goes into red blood cells
- the parasite bursts out of the rbc
- the infected blood is picked up by other mosquitos
- parasite reproduces asexually in mosquito guts
- parasite goes into mosquito saliva
- mosquito bites another human and infects them
what is a chromosome
strands of dna in a double helix shape
what is a gene
a section of a chromosome which controls a characteristic
what is the sex chromosome of a female
2 x
what is the sex chromosome of a male
x and y
what does a gene code for
a specific sequence of amino acids which form a protein
what is a genome
all of the genetic material in an organism
has the human genome been sequenced
yes, it was done by unravelling the double helix
what were the outcomes of hgp
- detailed information about the genome
- identification of new genes - genes analysed for mutations causing a mutation
- identification of new drug targets
- preventative medicine
- identification of mutations
what is an allele
an alternate form of a gene that form due to a mutation
what is a nucleotide
the molecules which DNA and RNA are made from
what is dna
Dna is a form of polymer called polynucleotide
what does a nucleotide consist of
a sugar, a nitrogen base and a phosphate
how many bases are there in dna
there are 4 bases: A,C,G,T
what is the monomer of DNA
nucleotides
what forms the backbone of DNA
phosphate and the sugar
how many bonds do G and C have
3 bonds
how many bonds do A and T have
2 bonds
what is the central dogma of molecular biology
the theory that states genetic material only flows in one way
how does the central dogma of molecular biology work
DNA turns into mRNA which turns into proteins
whats the process called when DNA turns into mRNA
transcription
what’s the process called when mRNA turns into proteins
translation
where does transcription take place
in the nucleus
where does translation take place
in the cytoplasm
what happens at transcription
DNA unwinds from the double helix shape. a hormone makes a copy of the DNA called mRNA. this mRNA leaves the nucleus and goes to the ribosomes
what happens at translation
each 3 bases of mRNA translate for a singular amino acid. the bases are ordered as the mRNA template of the DNA. this happens in the ribosomes in the cytoplasm. the amino acids are in the cytoplasm and are brought down to the ribosomes by carrier molecules to create a chain of amino acids which form a specific protein.
what happens after translation
the amino acid chain folds up to form a unique shape. this unique shape allows the protein to carry out its role effectively.
what is a mutation
a change when the genotype is copied differently from the original.
are mutations always bad?
no
what problems can mutations make
- enzymes’ active site is changed so a different substrate fits
- active site changed so no substrates fit
what is gene expression
when a gene codes for a protein which is synthesised in a cell
what is an allele
the same gene in a different form
what is the genotype
a combination of alleles
what is the phenotype
the effect of the alleles on characteristics of an organism
what is homozygous
It is when two alleles in an organism are the same
what is heterozygous
It is when 2 alleles are not the same. The genotype is heterozygous
what is a dominant allele
an allele which is always expressed
what is a recessive allele
an allele which can only be expressed if there are 2 present
how are some diseases inherited
the inheritance of some faulty genes
what is polydactyl caused by
a dominant gene
what is polydactyl
a disease when a person has extra toes or fingers
what is cystic fibrosis
a disorder of cell membranes
wwhat is cystic fibrosis
a disorder of cell membranes
what is cystic fibrosis caused by
it is caused by a recessive allele
what is gene therapy
when a patient is given a healthy version of defectiv gene
is there a cure to inherited diseases
NO
what is embryo testing
when embryos are tested during pregnancy for alleles which cause inherited diseases.
what are the 2 types of embryo screening testing
- amniocentesis
- CVS
how does amniocentesis work and the pros and cons
involves removing the amniocentesis fluid (the fluid surrounding an unborn baby in the womb) and testing it. Cna only happen to someone women who have a high chance of genetic disorders. can also only happpen between 15-20 weeks of pregnancy. after having the test done there is a 0.5-1% chance of miscarriage.
how does chorionic villus sampling work? also state the pros and cons while you’re at it
involves removing a bit of cells form the placenta using a needle and forceps.
The procedure can be descirbed as painful although there may be painful experiences which can be described being similar to cramps 1 or 2 days afterwards. Can happen 10-12 weeks during pregnancy.
risk of miscarriage is 2%.
what are the advantages of genetic screening
- fewer people with cycstic fibrosis are born which reduces health cost over time
- allows parents to finanically and emotionally prepare to live with a child with cycstic fibrosis
- reduces the number of people living with geneti disorders
what are the disadvantages of genetic screening
- puts the embryo at risk - higher chance of miscarriage
- it encourages abortion - religious people argue that the child has a right to life
- may cause harm to the mother
