B6 Inheritance, Variation and Evolution Flashcards
what is mitosis
formation of two genetically identical cells from 1 cell
what is meiosis
formation of 4 genetically non-identical cells (gametes) from 1 cell. These cells have half the genetic material of a normal cell.
how many chromosomes are in 1 cell
46 (23 pairs of chromosomes)
describe the stages of meiosis
-cell copies it’s genetic information so there is double the normal amount
-cells divide into two cells each with a full set of 23 pairs of chromosomes
-This cells then divide again into four cells each with 23 chromosomes, these cells are all genetically distinct
what is a gene?
what information does a gene carry?
a small section of DNA on a chromosome
triplets of bases code for a specific amino acids which together can form proteins via protein synthesis.
what is a genome
all of the genes for an organism
what are nucleotides made of and where are they found
they comprise the DNA and are made of a sugar molecule, a phosphate molecule and an organic base (of which there are four different types).
what are the four bases and which ones match with which
A with T and G with C
describe the stages of protein synthesis
-the DNA unzips and is copied by mRNA: the sequence of bases for making the protein (this is because the DNA cannot leave the nucleus).
-the mRNA then passes through the ribosomes (which are in the cytoplasm)
-The corresponding amino acids are brought to the ribosome and joined and folded to form a protein (proteins have a unique 3D structure).
what is a phenotype
All of the physical characteristics of an organism
what does being polydactyl mean
having extra fingers or toes as a result of a dominant allele
what is cystic fibrosis
a disorder that produces thick mucus in the airways or pancreas caused by a recessive allele
what are the alleles of a man and woman
man= XY woman= XX
what is evolution
the change in shared characteristics over time
explain the theory of evolution
-variation between organisms created through mutation and sexual reproduction
-if the mutation gives a survival advantage the organism is more likely to survive and pass on those genes to it’s offspring
-Over many generations, the frequency of the mutation increases in the population: evolution
what is selective breeding
where people will choose which organisms to breed in order to create valuable traits
What are two advantages of sexual reproduction?
Produces variation in offspring –> allows natural selection and evolution to occur.
Allows humans to selectively breed animals to produce offspring with the best combination of characteristics.
What are three advantages to asexual reproduction?
Only one organism required.
–>Less energy required and faster.
–>Lots of offspring can be produced quickly in favourable conditions.
What is the importance of non-coding sections of DNA (do not code for proteins)?
Determines which genes are expressed
What is genotype?
The combination of alleles that an individual has
name the 8 things living things are divided into
domain, kingdom, phylum, class, order, family genus, species
what are the three domains
bacteria, Archaea, eukaryotes
explain how genetic engineering works
-genes from chromosomes are cut out using restriction enzymes leaving a sticky end
-a virus or bacterial plasmid is cut with the same enzyme
-they are joined together by DNA ligase enzymes
-the combined loop is placed in a vector and allowed to multiply as it will now contain the modified gene
what are some advantages and disadvantages of GM crops
Adv:
-improve growth rate
-can make crops grow in hotter or colder regions
-plants can make their own pesticide or herbicide
-greater yields can help solve world hunger
Dis Adv:
-may effect wild flowers and insects
-we don’t know how GM crops effect humans
-could create super weeds and pests
