Section 3 - Genetics Flashcards
Sexual reproduction and meiosis, DNA, Genetic diagrams, Variation, The human genome project
True or False? A zygote is a haploid.
False. A zygote is formed when a male gamete fuses with a female gamete, so it ends up with the full set of chromosomes.
Name the type of cells that are formed when a cell divides by meiosis. How many of these are formed each time a cell undergoes meiosis?
Gametes are formed by meiosis. There are four gametes produced each time a cell divides in this way.
What are the four different bases in DNA?
A(adenine)
T(thymine)
C(cytosine)
G(guanine)
What is bigger - a gene or a genome?
A genome is bigger than a gene. The genome is the entire DNA of an organism. A gene is a section of a DNA molecule that codes for a specific protein.
Which bases in DNA pair together? What holds the base pairs together?
A & T, C & G. The pairs are held together with weal hydrogen bonds.
Describe the structure of a nucleotide.
A nucleotide consists of sugar, a phosphate group and one of the four different bases. The base is attached to the sugar.
How do you extract DNA from some strawberries?
Mash the strawberries, put them in a beaker containing a solution of the detergent and salt and mix together. Filter the mixture to get the froth and big, insoluble bits of cell out. Gently add some ice cold alcohol to the filtered mixture. Carefully fish out the stringy white precipitate with a glass rod.
What does homozygous mean?
You have two alleles for a particular gene that are the same.
What alleles must you have to display a recessive characteristic?
You must have two recessive alleles for a particular gene.
Describe the difference between genotype and phenotype.
Genotype is the combination of alleles you have, whereas phenotype is the characteristics you have.
How do mutations introduce genetic variation into the populations?
Mutation change the sequence of bases in DNA, which can result in an allele when they occur in a in a gene.
When a mutation occurs, what is the most common outcome for the phenotype?
Most mutations are neutral — they have no effect on the phenotype.
What did the human genome project aim to do?
To find every single human gene in order to make a complete map of the human genome?
The human genome project may allow doctors to know what genes predispose people to certain diseases. Give one advantage and one disadvantage of this knowledge.
It would enable people to get individually tailored advice on the best diet and lifestyle to help avoid their likely health problems. However, it might allow employers and insurers to discriminate against those people who are genetically likely to get a disease.
