biology paper 2 - b13

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what is a sexual reproduction
no fusion of gametes, and involves only one parent, no mixing of genetic information, meaning the offspring is genetically identical to parent (clone)
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what process is involved in asexual reproduction
mitosis
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what is sexual reproduction
when the joining of male and female gametes formed by meiosis
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what process is involved in sexual reproduction and what does this mean
meiosis, it leads to the formation of non-identical cells, variation
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what are some examples of asexual reproduction
yeast (fungi) and bacteria, cells in our body reproduce asexually to replace worn out tissues
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in plants what are the gametes
pollen and the egg cells
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in animals what are the gamtes
egg cells (ova) and sperm
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how many chromosomes do the egg and sperm have
they each have 23
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how amny chromosomes does a zygote have
46 chromosomes
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what happens before meiosis begins
each chromosome is copied exactly, these two copies stay attatched to one another. so 92 chromosomes
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after doubling the chromosomes what happens
the cell divides twice to form 4 gamtetes, each with a signle set of chromosomes
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the gametes that are produced, are the gentically different
yes, they contain random mixtures of the original chromosomes, introducing variation
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what does each sex cell have
a single set of chromosomes
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when sex cells join in fertilisation, what does the single new cell have
full set of chromosomes - 46
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what is restored at fertilisation
the normal amount of chromosomes, this new cell divides by mitosis
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when the new cell divides by mitosis , does the number of cells increase or decrease
increases, and embryo develops, cells differentiate
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what are the differences between sexual and asexual reproduction
asexual - mitosis, no variation but sexual - meiosis, variation
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what is DNA
a polymer, a long molecule made up of repeating units. these are very long strands that twist and spiral to form a double helix structure
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what are genes
small sections of DNA, on a chromosome
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what is genetic information
coded information that determines inherited characteristsics
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what do your chromosomes contain
thousands of your genes
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what does each gene code for
a sequence of amino acids to make a specific protein, that control your cell chemistry
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what was the human genome project
trying to sequence the human genome, chopping up the DNA, read base sequences, they finished early and underbudget, technology improved so fast during the project
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what is the genome of an organism
entire genetic material of the organism, includes all of chromosomes, gnetic material found in mitochondria
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what contains their own DNA
the mitrochondria, always inherit from mother as it comes from the mitochondria in the egg
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what can the human genome do
it has the ability to make many different proteins from the same gene by using it in different ways, switching part of a gene off or on
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what does sequencing genomes of bacteria/ viruses help us to do
identify the causes of diseases, very quickly, to give correct treatment
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why does the human genome matter
as it helps us understand inherited disorders like cystic fibrosis and sickle cell disease
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if we understand more about the human genome - what could these mean
more likely to predict the risk for each individual, more choices to help reduce the risk, better at choosing the correct treatment, more chance of overcoming it by medicine or replacing faulty genes
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what are chromosomes and where are the found
long threads of DNA, containing thousands of genes, in the cells nucleus
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what is a gene
small sections of DNA on chrmosomes,
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what is an allele
the different forms of a gene for a particular characteristic
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what do alleles do
each allele codes for a different protein
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what do the combination of alleles determine
your characteristics
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what is a homozygote
an individual with two identical alleles for a characteristic - BB or bb
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what is heterozygote
an individual with different alleles for a characteristic - Bb
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what is a genotype
describes the alleles present/ genetic makeup of an individual regarding a particular characteristic - Bb or bb
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what is a phenotype
describes the physical appearance of an indivdual regarding a characteristic - black or brown fur in a mouse
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what is an allele
the particular form of information in that position on an individual chromosome.
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what could the gene for a coat colour in mice be
black(B) or brown (b) allele in place. the mouse inherits one allele from each parent, the offspring will have two alleles controlling the colour of the mouse (black or brown)
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where is the dominant allele always expressed
in the phenotype
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is the dominant allele lower or upper case
upper case, capital letter
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if the mouse was black what alleles could be inherited from its parents - using B
BB or Bb - both have a dominant B
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what happens when no dominant allele is present
the phenotype is recessive
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if the mouse inherited two recessive alleles, what could would it be
brown, bb
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if recessive means having two lower case letters, is the organism heterozygote or homozygote
homozygote
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what is a genetic cross
condering the potential offspring from two known parents, you need to understand the possible phenotypes for the offspring
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what is a punnett sqaure
it allows us to predict the outcome of different genetic crosses
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what does the punnett square give us
genotype of parentts, possible gametes that can be formed by these, how these may combine to form the characteristic in their offspring, the possible genotypes allows you to know the possible phenotypes too . it will give you probabilities
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what is the sex chromosome for females and males
** - female and XY - male
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when the cells undergo meiosis to form gametes, the human egg contains X and whata anotu the sperm
half X half Y
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how can yoy determine the probaility the inheritance of sex
a punnett square
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what is the ratio of having a girl or boy
50:50
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what can disorders change for the indivdual
a chahge in bases or coding of our genes
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what is polydactyly
extra fingers or toes, caused by a dominant allele
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how can polydactyly happen
a parent having it, or a dominant allele
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if you have polydactyly and are heterozygous, what is the chance your children will have this and why
50% - half of your gametes contain the faulty dominant gene
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if you have polydactyly and are homozygous, what is the chance your children will have this and why
100%
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what is cystic fibrosis
genetic disorder, affecting lungs/organs, disorder of the cell membranes, prevents movement of certain substances, mucus made by cells becomes thick/sticky, organs become clogged, cant work properly, pancreas cant extcrete enzymes, infertility
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what are some treatments for cystic fibrosis
physiotherapy, antibiotics to help keep lungs clear of mucus and infections. enzymes are used to replace the onces the pancreas cant make and to thin the mucus. no cure
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how is cystic fibrosis causes
recessive allele, inherited from both parents, usually born from parents who do not suffer from disorder
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what do the parents of cystic fibrosis kids usually have
they have a dominant healthy alle but both carry the recessive allele of cystic fibrosis.
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what are carriers
a person that has inherited a recessive allele for a genetic trait or mutation but usually does not display that trait/symptoms of the disease.
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what is genetic engineering
replacing faulty alleles with healthy ones
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how do you screen an embryo or fetus
harvest cells from developing individual, it is done by amniocentesis or chorionic villus sampling
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when and what does amniocentesis involve
cariied out 15-16 weeks of pregnancy, involves taking some of the fluid from the developing fetus, containing fetal cells, which can be used in gentic screening
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when and what does chorionic villus sampling involve
chorionic villus sampling of embryonic cells is done earlier 10-12 weeks, taking a small sample of tissue from the devloping placenta, privides fetal cells to screen
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what risks do these methods have
a miscarriage
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what is involved when the cells have been collected
they need to be screened, DNA is isolated from embryo cells and tested for specific disorders
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what if the screening shows that the fetus is affected
gives parents a choice, keep it or abortion, and try again for a healthy baby
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what are some concerns about embryo screening
distressing for parents if miscarriage of healthy baby (done unnecessarily) still chance of false information, econimc cost - expensive, decisions to make if proved affected can be difficult - emotional, religious, science
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Other cards in this set

Card 2

Front

what process is involved in asexual reproduction

Back

mitosis

Card 3

Front

what is sexual reproduction

Back

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Card 4

Front

what process is involved in sexual reproduction and what does this mean

Back

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Card 5

Front

what are some examples of asexual reproduction

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