Topic 3 - Genetics Flashcards
What are gametes?
Examples of gamete’s ?
Gametws are reproductive cells.
Sperm and egg cells
How many chromosomes does a human cell nucleus contain?
46
What’s the diploid number for a human ?
46
What’s the haploid number for a human?
23
Are gametes diploid are haploid?
Gametes are haploid
What does the male gamete fuse with to produce a zygote?
A male gamete guess with the female gamete to produce a fertilised egg. (Zygote)
What’s a zygote?
A zygote is a fertilised egg
What happens to the zygote for it to become an embryo?
The zygote undergoes cell division by mitosis to become an embryo
How is mitosis differnt to meiosis?
Mitosis produced identical cells however meiosis produces unidentical cells
What is the result of meiosis?
At the end of meiosis, you get four haploid cells, these are the gametes. They are all genetically differnt
What does meiosis produce and where does it happen?
Meiosis produces gametes and it happens in the reproductive organs (ovaries and testies)
What are the two types of reproduction?
Sexual
Asexual
In which type of reproduction is mitosis used in? Which one is meiosis used in
Asexual- mitosis
Sexual- meiosis
Advantages and disadvantages of asexual reproduction…
Advantages- produce offspring quickly because reproductive cycle is fast. Only one parent is needed.
Disadvantages- no genetic variation between offspring. Whoel poopulafion could be affected by something.
Advantages and disadvantages of sexual reproduction?
Advantages- sexual reproduction creates genetic variation within the population. This means if the environment changes, some of population will survive.
Disadvantages- takes more time and energy than asexual reproduction. Two parents are needed
Is a dna strand a polymer or a monomer?
What are DNA strands made up of?
DNA strands are polymers made op of many repeating units called nucleotides.
What is each nucleotide on DNA made up of?
A sugar
A phosphate
A base
What forms the backbone in a dna strand?
The sugar and phosphate
What are the 4 bases in dna?
A,T
C,G
What is the shape of DNA ?
A double helix
What are the complementary base pairs joined together by?
Complementary base pairs are joined together by weak hydrogen bonds.
What are chromosomes and where are they found?
-Chromosomes are long, coiled up molecules of DNA.
- chromosomes are found in the nucleus of eukaryotic cells
What is a gene?
A gene is a section of DNA on a chromosome that codes for a particular protein/ trait
Practical for extracting DNA from a fruit cell. What will the detergent do? What does the salt do?
What will happen at the end?
1) mash strawberry and putting them in a beaker containing a solution of dergent and salt. Mix it.
- the detergent will break down cell membranes to release DNA.
- the salt will make the DNA stick together
2) filter the mixture to get the froth and big, insoluble bits of cell out.
3) gently add ice cold alcohol to the filtered mixture.
4)the DNA will start to come out the solution as it’s not soluble in cold alcohol. It will appear as stringy white precipitate.
What is protein synthesis?
The production of proteins
What are proteins made up of?
Proteins are made up of Amino acids
Why do amino acid chains fold up?
To give each protein a different shape, therefore a different function
What decides the order of amino acids in a protein?
The order of bases in a gene decided the order of amino acids in a protein
What’s each amino acid coded for by?
A sequence of 3 bases on a gene, this is called a base triplet
What makes up an organisms genome?
All an organisms DNA (including non- coding regions)
What are the 2 stages of protein synthesis?
1)transcription
2) translation
Where does protein synthesis happen?
In the ribosomes contained in cytoplasm
Why is transcription needed in protein synthesis?
Because the DNA is too big to leave the cell nucleus and it has to get to the ribosomes
What is used in transcription?
mRNA, it also uses U instead of T as a base.
What is RNA polymerase?
RNA polymerase is the enzyme involved in building RNA molecules that are complementary to a portion of one strand of the DNA double helix
What are the stages of transcription in protein synthesis?
1)RNA polymerase binds to a region of non-coding DNA in front of a gene.
2) the two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA
3) it uses the coding DNA in the gene as a template to make the mRNA . Bass pairing between the DNA and RNA ensures that the mRNA is complementary to the gene
4) mRNA moves out tbe nucleus and joins with a ribosome
What are the stages of translation in protein synthesis?
1)Amino acids are bought to the ribosomes by tRNA (transfer RNA)
2)the order amino acids are bought in matches the order of the codons.
3)part of the tRNA structure is called an anticodon- its complementary to the codon for the amino acid, this makes sure the amino acids are bought to the ribosome in the correct order.
4)the amino acids are joined together at the ribosome, this makes a polypeptide (protein)
What is a mutation?
rare, random change to an organisms DNA base sequence
What happens if a mutation happens in a gene?
If a mutation happens in a gene it can produce a genetic variant/allele
What happens if the allele codes for a different sequence of amino acids ?
If the allele codes for a differnt sequence of amino acids it may change the shape of the protein and its activity . This could end up changing the phenotype of an organism
Can mutations in the noncoding region of DNA affect the organisms phenotype?
Mutations in the non coding region can also alter the phenotype of an organism because of RNA polymerase
What is an allele?
Alleles are different versions of the same gene
How many versions of an allele do you have on every gene of your body?
You have two versions of every gene on your body- one on each chromosome in a pair
What does it mean if 2 of an organisms alleles are the same ?
It’s homozygous
What’s it’s called if two alleles for a particular gene are differnt?
If two alleles for a particular gene are different , its heterozygous
How is a dominant allele presented?
With a capital leter
How is a recessive allele represented?
With a lowercase letter. Eg- c
Which allele will determine the characteristic of a gene if there’s one dominant allele and one recessive allele. EG: Cc
The dominant allele with determine what characteristic is present
How would an organism display a recessive characterisitc?
The organism must have two recessive alleles
What’s your genotype?
Your genotype is the combination of alleles you have.
What is this called?
A punnet square
What are the chromosomes to show a baby being a male?
Female?
Male - XY
Female - XX
What allele is cystic fibrosis caused by?
A recessive allele
Why won’t everyone with a recessive allele get cystic fibrosis?
Because they are carriers. To actually get cystic fibrosis you must receive both recessive alleles for it.
What did Gregor Mendel help with?
Gregor Mendel did discoveries about inheritance. He also did experiments with pea plants and became the foundation of modern genetics.
What 3 important conclusions did Mendel come too from his pea plant experiments? Hereditary units (genes)
1) characteristics in plants are determined by ‘hereditary units’
2)hereditary units are passed onto offspring unchanged from both parents, one unit from each parent
3)hereditary units can be dominant or recessive.
What’s colour blindness caused by?
Colour blindness is causes by a faulty allele carried on the X chromosome.
What’s haemophilia caused by?
A fault gene on the X chromosome
Why are some sex-linked disorders such as colour blindness more common in males?
Because males only have one X chromosome so they only have one allele for sex linked genes. This means females need 2 copies of the recessive allele to get the disorder, but males only need one.
What are the 4 potential blood types in humans ?
A,B,AB,O
What will the offspring’s blood type be if they inherit one I^A from their mother and one I^B from their father?
AB
What will am offspring’s blood type be if they inherit one I^O from each parent and why?
Because the genotype I^O is reccesive , the blood type will be O
Is the blood type I^B dominant or reccesive ?
Dominant against I^O, codominant with I^A
The two reasons for variation within a species?
-generic
-environmemtal
What’s genetic variation in a species caused by?
Genetic variation within a species is caused by organisms havigng different alleles.
What could environmental variation within a plant be causes by?
Sunlight
What are mutations?
What happens when mutations occur within a gene?
Changes to the base sequence of DNA.
Mutations within a gene result in an allele or a different version of the gene
What does it mean if a mutation is neutral?
If a mutation is neutral, it means they don’t have any effect on the phenotype or am organism
What did the human genome project do?
-The human genome project mapped out 20,000 genes
-helped find 1800 genes related to disease, this has huge potential benefits for medicine
3 medical applications of the human genome project?
-prediction and prevention of diseases
-testing and treatment for inherited disorders
-new and better medicines
How did the human genome project help with PREDICTION AND PREVENTION OF DISEASES?
-If doctors knew the genes responsible for diseases we can get individually tailored advice on how to avoid our likely problems.
-doctors could check us regularly
How has the human genome project helped with TESTING AND TREATMENT FOR INHERETED DISORDERS?
Scientists can identify the genes and alleles that are suspected of causing an Inhereted disorder much quicker than they could in the past.
How has the human genome project helped find NEW AND BETTER MEDICINES?
Scientists can use knowledge To design new drugs that are tailored to people with a particular genetic variation .
What are the drawbacks of the human genome project and what do they mean?
1) increased stress- if someone knew they were susceptible to brain disease they could panicked every time they get a headache even if it was nothing.
2) geneism- people with genetic problems could come under pressure to not have children.
3) discrimination by insurers- life insurance could become expensive to get for people with genetic likelihood of a serious disease
