section 7 - reproduction and inheritance Flashcards
what is a gene
short section of DNA that codes for a particular protein
how many chromosomes in a human body cell
diploid - 46
what are different versions of the same gene
alleles - blue or brown eyes
what are two strands of DNA
double helix
what are the two strands held together by
chemicals called bases
what are the 4 bases
adenine, cytosine, guanine, thymine
which base is A paired with
T
which base is C paired with
G
what does DNA control
production of proteins - protein synthesis in a cell
what does each protein have
a particular number and order of amino acids
what decides the order of amino acids in a protein
the order of bases
how many bases in a codon
3
how do genes code for a particular protein
contain different sequences of bases
DNA also contains non-coding regions means…
they dont code for any amino acids
what cell are proteins made in
ribosomes in the cytoplasm
why cant DNA move out of the nucleus
its to big
what is the molecule that get the information from the nucleus to the ribosome
mRNA
what is mRNA made up of
sequence of bases that is shorter and a single strand
what is the enzyme that joins together the base sequence to make mRNA
RNA polymerase
what are the steps of transcription
- RNA polymerase brings a region of non-coining DNA in front of a gene
- the two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA
- it uses the coding DNA in the gene as a template to make mRNA. base painting between DNA and RNA ensures that mRNA is complementary to the gene.
- once made the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm
what does mRNA use instead of T
U - uracil that pairs with A
what are the steps of translation
- amino acids are brought to the ribosome by another RNA molecule called tRNA
- the order in which the amino acids are brought to the ribosome matches the order of the codons in mRNA.
- part of the tRNA structure is called an anticodon - it is complementary to the codon for the amino acid. the pairing of the codon and anticodon make sure that the amino acids are brought to the ribosome in the correct order.
- the amino acids are joined together by the ribosome. this makes a protein.
what cell decision is asexual reproduction
mitosis - genetically identical and contain exactly same genetic information
what is the definition of asexual reprodiction
involves one parent. the offspring have identical genes to the parent - so there is no variation between parent and offspring
definition of mitosis
when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes
what is the 1st stage of mitosis
interphase - The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
what is the 2nd stage of mitosis
Prophase- The DNA in chromosomes and their copies condenses to become more visible. The membrane around the nucleus disappears.
what’s the 3rd stage of mitosis
Metaphase Chromosomes and their copies line up in the middle of the cell.
what the 4th stage of mitosis
Anaphase Chromosomes and their copies are pulled to different ends of the cell by cell fibres
what is the 5th stage of mitosis
Telophase New membranes form around the chromosomes at each end of the cell.
what is Cytokinesis
The cell membrane pinches in and eventually divides into two daughter cells.
what is mitosis used for
growth and repair
how many daughter cells in mitosis and how many chromosomes
2 genetically identical diploid cells with 46 chromosomes
what are gametes
sperm and egg cells
how many chromosomes in gametes
haploid 23
what does the fuse of gametes cause
zygote with full set of chromosomes
definition of sexual reproduction
involves the fusion of male and female gametes because there are to parents, the offspring contain a mixture of their parents genes
where does meiosis happen
gametes
definition of meiosis
produces 4 haploid cells whose chromosomes are not identical
what happens in division 1 of meiosis
- DNA duplicates and one arm is the exact copy of other arm
- chromosomes line up in pairs at centre. one chromosomes in each pair comes from mother and one from father.
- the pairs are pulled apart so new cell has copy of Rach chromosome. some are mothers and some are fathers go into each new cell
- each new cell with have a mixture of mothers and fathers chromosomes which cause genetic variation
what happens in division 2 of meiosis
- the chromosomes line up again in the centre of the cell. the arms of the chromosomes are pulled apart
- 4 haploid gametes. each gamete only has a single set of chromosomes and they are genetically different
4 differences between mitosis and meiosis
mitosis produces 46 chromosomes - diploid. meiosis produced 23 chromosomes - haploid
mitosis produces 2 daughter cells, meiosis produces 4.
mitosis is for growth and repair and asexual reproduction and meiosis is for gametes only.
mitosis daughter cells are genetically identical. meiosis are all genetically different.
what is the male part of the plant and what does it contain
stamen - filament and anther
what is the function of the anther
contains pollen grains - produce male gametes
what is the function of the filament
supports the anther
what is the famale part of the plant
carpel - ovary, style and stigma
what is the function of the stigma
pollen grains attach to
what is the function of the style
supports the stigma
what is the function of the ovary
contains female gametes inside ovules
what is pollination
transfer of pollen from an anther to a stigma so male gametes can fertilise the female gametes in sexual reproduction
what is cross-pollination
sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another
what helps a plant pollinate
insects , wind
how are plants adapted for insect pollination
- bright coloured petals to attract insects
- scented to attract
- big, sticky pollen grains to stick to insects as they go from plant to plant
- the stigma is also sticky so that any pollen will stick
how are plants adapted for wind pollination
- small dull petals
- a lot of small and light pollen grains to be carried by the wind
- long filament that hang the anthers outside the flower to get blown by the wind
how are plants adapted for wind pollination
- small dull petals
- a lot of small and light pollen grains to be carried by the wind
- long filament that hang the anthers outside the flower to get blown by the wind
- a large feathery stigma to catch pollen that hangs outside flower to
what is fertilisation
the fusion of gametes
what are the steps of plant fertilisation
- After pollen has landed on the stigma, it grows a pollen tube down through the style to the ovary.
- The nucleus of the pollen grain travels down the pollen tube and fertilises the nucleus in the ovule.
- The fertilised ovule develops into a seed. The seed contains the plant embryo, which contains genetic material from both parents. The ovary develops into the fruit.
what are the conditions for a seed to germinate
water - to activate the enzymes that break down the food reserves in the heat
oxygen - for respiration
suitable temp - for enzymes to work
how do germinating seeds get energy
from food stores
what conditions would each of 4 tubes have in to investigate the conditions needed for germination
tube 1: water, oxygen, room temperature (control).
tube 2: no water, oxygen, room temperature
tube 3: water, oxygen, low temperature
tube 4: water, no oxygen, room temperature
what are the observations from the conditions needed for germination
only see germination in tube 1 because all conditions are needed for germination are present
what is a natural method for plants to clone
- runners - fast growing stems
- the runner take root at various points
- the new plants are clones of the parent plant
what is an artificial method to clone plants
taking cuttings
cuttings kept in moist conditions until ready to plant. cloned plant
what is the prostate gland for?
produce liquid thats added to sperm to make semen
what is the urethra for
carries sperm or urine out of the body
what is the testis for
where sperm is made
what is the vas deferens
carries sperm from testis towards urethra
what is the erectile tissue for
swells up when filled with blood to make penis errect
what is the endometrium
lining of the uterus with good blood supply for implantation of an embryo
what are female secondary characteristics
- extra hair on underarms or pubic area
- hips widen
- development of breasts
- ovum release and start of periods
what are male secondary characteristics
- extra hair on face and body
- muscles start to develop
- penis and testicles to enlarge
- sperm production
- deepening voice
what does FSH stimulate
egg to mature in follicle, stimulates ovaries to produce oestrogen and oestrogen inhibits release of FSH
what does oestrogen stimulate
lining of uterus to grow, stimulates release of LH
what does LH stimulate
stimulates release of egg at day 14
what does progesterone stimulate
maintains the lining of the uterus. the level of progesterone falls, the lining breaks down. inhibits the release of LH and FSH.
what is the placenta for?
blood of embryo and mother to get very close to allow the exchange of food, oxygen and waste
what is the amniotic fluid for?
protects the embryo against knocks and bumps
what is your genotype
the alleles that you have
what is the phenotype
the characteristics the alleles produce
what is homozygous
two of the same alleles
what is heterozygous
two different alleles
what are coo dominant alleles
both characterists from both alleles like blood group AB
what are male chromosomes
xy
what are female chromosomes
xx
what is variation caused by
genetic and environmental factors
what is a genetic factor
eye colour, hair colour
what is an environmental factor
poor diet can stunt growth
4 things plants are strongly affected by
- sunlight
- moisture level
- temperature
- mineral content in soil
what is the theory of evolution
life began as simple organisms from which more complex organisms evolved
what is natural selection
- genetic variation in characterists
- most suitable characterists for that environment would have a better chance of survival
- breed and reproduce
- pass on alleles
how do mutations produce genetic variant
change the sequence of the DNA bases in a gene
how do mutations increase variation
lead to different phenotype
what are 2 reasons for the chance of mutation to be increased from exposure
- ionising radiation
- chemicals called mutagens like in tabacoo
what is a superbug
bacteria that are resistant to most known antibiotics and are becoming more common
