unit 2.4 characteristics and inheritance.

Frage	Antworten
Q: What is genetics?	A: genetics is the study of inherited (obtaining) characteristics called traits.
Q: What are traits and alleles?	A: alleles are different forms of the same gene located at the same point of homologous chromosomes. Traits are inherited characteristics.
Q: What is pure breeding?	A: Pure breeding is where all individuals have the same genetic information for a characteristic generation after generation.
Q: Define dominant and recessive trait.	A: Dominant trait is observed in the outward appearance of a heterozygous ( a pair of genes where one is dominant and one is recessive) individual
Q: What alleles represent dominant trait and recessive characteristics	A: the allele for the dominant trait is represented by an upper case letter -R relating to the name. the recessive characteristic is represented by the lower case of the same letter - r.
Q: What is rr and RR represetned as?	'little r, little r' and 'big R', big R'
Q: what is homozygous and heterozygous?	A: homozygous means having 2 IDENTICAL alleles on homologous chromosomes. heterozygous means having 2 DIFFERENT alleles on homologous chromosomes.
Q: Define Punnett squares.	A: A type of grid used to show the gametes of each parent and their possible offspring. the possible gametes produced by one parent are shown across the top, the gametes from the other parent are shown down the side. in each square is a possible outcome of fertilization.
Q: Define genotype and phenotype.	A: genotype is genetic information carried by an individual. phenotype is observable characteristics of the individual; the way the genotype is expressed.
Q: What happens if a sperm contains an X or Y chromosome fertilising the egg?	A: if a sperm contains an X chromosome fertilizing an egg the offspring will be a female (XX). if a sperm carrying a Y chromosome fertilises egg then the offspring will be a male (XY).
Q: What are sex linked genes?	A: genes present on the sex chromosomes
Q: What is the difference between the X and Y chromosome?	A: The X chromosome is longer than the Y chromosome and carries more genes. Most sex linked genetic traits in humans are carried on the X chromosome. The Y chromosome is smaller and contains less genes. The X chromosome contains a colour blindness gene and the Y dosen't.
Q: Define pedigree.	A: a diagram used to show patterns of inheritance over generations.
Q: give 2 examples of sex linked characteristics	A: Haemophilia and Duchenne muscular.
Q: Define chromosomal abnormality	A: when chromatids fail to separate during meiosis the child is born with an extra chromosome or part of a chromosome.
Q: How can mistakes happen when DNA is being copied and what is the change called?	A: The base sequence is changed and mistakes occur in the manufacture of proteins. The change is called mutation.
Q: Name types of mutations.	A: Silent mutations, nonsense mutations, missesce mutations and frameshift mutations.
Q: Define Mutagens.	A: Agents that cause mutation
Q: Define carcinogen.	A: a substance capable of causing cancer in living tissue.
Q: Common agents that cause mutations can happen in Chemical, Biological and radiation ways, give examples.	A: Radiation - X rays, radiosotopes, UV light, UV tanning beds. Chemical - cigarette smoke asbestos, mustard gas benzene, ethyl alcohol etc. Biological - hepatitis B, virus, liver cancer, human papilloma, cervical cancer.

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unit 2.4 characteristics and inheritance.

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