Sb3 Genetics Flashcards
What does sexual reproduction involve
Fertilisation if a female sex cell by a male sex cell
Clones definition
Offspring that are genetically identical to the parent
Advantages and disadvantages of sexual reproduction
Advantage - combines characteristics from both parent and so produces offspring that are diffrent from one another this is an advantage if their are any changes to offspring environment as they have more genetic variation meaning that their is a greater chance some offspring will be able to adapt and survive and be better suited to the new environment
Disadvantage- it is time consuming to find a mate and then hard to impress a mate
Advantages and disadvantages of asexual reproduction
Advantage- asexual reproduction is much faster as their is no need to find a mate
Disadvantage - their is no genetic variation within offspring so if their was to be a change in environment they will either all die or all live . For example if their was a new disease on a potato farm and one of the potatoes died that means all the potatoes would die aswel as they all have the exact same genetic info
What’s a zygote
A fertilised egg cell
What does a zygote then form
It then forms a ball cells called an embryo through mitosis
What’s found in DNA
In dna is the code for the instructions of an organsim
Genome definition
The complete DNA of an organism
What are genes
The sections of a DNA molecule ( dna molecule if unravelled would be 2m long so the dna is tightly coiled so it takes up less space each coil is a section or chromosome their are 46 coils .)
What is a chromosome made up of
Proteins and DNA
What are proteins
Polymers made by linking different amino acids together in a chain
Protein synthesis steps and summary
Transcription - taking a single gene and copying it into mRNA
Translation - taking the mRNA and making it into a protein
What are genes and their significance
Small sections of DNA that have a specific sequence of bases and so are able to code for a particular amino acid and when combined will form a particular protein .
Why do we have to make a copy of a gene to make a protein
Because the DNA is to bug it can’t leave the nucleus
What’s is mRNA
mRNA copy of a single gene that gets taken to the ribosome from the nucleus
Structure of mRNA vs DNA
1) shorter than DNA as it’s only a single gene long
2) only a single strand rather than a double strand like DNA
3) instead of thymine it contains uracil
Transcription process
- The DNA strands will separate just ahead of the RNA polymerase to make space for the RNA polymerase to go through
-RNA polymerase will go through the gene you want to copy and it will read each complementary based pairs and will copy it - now you have a copy which is mRNA which is free to leave the nucleus and head to a ribosome
What is a triplet / codon and what does it do
A group of three bases that codes for a specific amino acid
Translation process
- once mRNA reaches the ribosome they bind together
- the ribosome then builds the protein by adding one amino acid at a time
-the amino acids are brought to the the ribosome by a molecule called tRNA - tRNA molecules have the amino acid at the top and anti codon at the bottom ( complementary to the three bases on the mRNA that code for the amino acid the tRNA is carrying
The tRNA brings down the correct amino acids int he correct order and then the ribosomes job is to then join them and start building up a chain of amino acids - this process repeats down the chain until, the ribosome detaches itself
- last step the chain folds up upon itself to form a protein
What is DNA
A chemical polymer ( made up of lots of similar units stuck together ) that all our genetic material is made up of
What is a double helix
2 strands of DNA spiralled together
What is a gene
Small section of DNA that codes for a protein ( small segment of a chromosome )
What’s the genome
Entire set of genetic material in an organism .
What are Alleles
Diffrent versions of the same gene
How many alleles of each gene do we have
2 one from each parent
Homozygous meaning
If the two alleles u get from ur parents are the same they are homozygous alleles
Heterozygous meaning
If the two alleles u get from ur parents are diffrent they are heterozygous alleles
Whats a dominant allele
The allele that gets expepreseed out of two heterozygous alleles
What’s phenotype
Physical characteristics you get from ur genotype
Gregor Mendel what did he do
Known as the founding farther of genetics he studied pea plants to see how traits like color where passed on through generations
What did Gregor Mendel do
He crossed different color plants together to see what their offspring would look like to ( green and yellow pea pods ) to come to the conclusion that their must be something being passed on from one generation to the next . He called them hereditary units
What is a mutation
A spontaneous change in the DNA base sequence
What increases the risk of mutations
1) carcinogens
2) certain typed of radiation like X-rays
What is a substitution mutation
When one of the bases is changed for another random base. Changing the triplet and code and therefore the amino acid if codes for
What is an insertion mutation
An extra base is inserted into the sequence . It’s worse that substitution as it means all the bases are shifted along by one. Meaning the amino acid chain afetr the point of insertion would be completely diffrent
What is deletion mutation
When one of the bases is deleted from the sequence . Everything shifts one space to the left after the point of deletion .
