genetics Flashcards
name 3 applications of genetics and whtey can do
- crop breeding and animal husbandry - improve yield, pest resistance, widen geographical range and make harvesting easier
- medical - help identify affected individuals and carriers of inherited diseases, identify risk factors and potential for gene-based therapies
- forensic - genetic fingerprints for identification e.g. paternity testing, criminal investigations and identification of disaster victims
name the 4 different structural types of chromosomes and how they differ
Metacentric - P and Q arm are even
Submetacentric - Q arm is longer than normal
Acrocentric - P arm is shorter than normal
Telocentric - P arm is missing
what is the P and Q arms of a chromosome
P = upper and Q = lower
what is karyotype evolution and give an example
where chromosome rearrangements contribute to evolution e.g. chromosome numbers in zebra
what can cause changes in chromosome numbers
- chromosome fusion = two telomeres and one centromere lose function
- chromosome fission = a new centromere must develop and telomeres must be added at new ends
what is a globin gene
a duplicated gene - can develop at different functions over time resulting in gene and protein families
what are paralogs and explain the example of hedgehog genes
paralogs = related copies of a gene in a single species
e.g. Sonic, desert and Indian hedgehogs are paralogs
what are Orthologs and give an example
genes in different species that are derived from a common ancestor e.g. Sonic, desert and Indian are orthologs of Drosophila hedgehog
what is ploidy
it refers to the number of sets of chromosomes in a cell; where one set = n chromosomes, therefore n is monoploid, 2n is diploid, 3n is triploid and so on
what is aneuploid
extra or missing chromosomes from a set e.g. 2n+1 and 2n-1
what is a monohybrid cross/ punnet square used for
to determine the phenotypes and genotypes of offspring in the first generation
what is a phenotype
the physically presented genetics of a gene
what is the difference between a dominant and recessive allele
a dominant allele will always be displayed whether or not it is heterozygous or homozygous, whereas a recessive allele must be homozygous
what happens in co-dominant alleles and give an example
both traits are expressed as all traits are dominant e.g. blood typing; A, B, AB, or O
what happens with incomplete dominant alleles
all traits are dominant but they blend together e.g. red and white flowers produce pink flowers
what is crossing over and at what point during meiosis does it occur
crossing over is the swapping of chromosomes from both parents and it occurs during prophase 1
what is non-disjunction and what can it cause
this is where chromosomes do not separate properly/ fail to separate causing a variety of syndromes depending on which chromosome this mutation occurs on e.g. Down Syndrome
what is Turner syndrome and what does it cause
single sex chromosome (XO); causes females to be infertile as they do not go through puberty to develop reproductive organs
what is Klinefelter’s syndrome and what does it cause
an extra sex chromosome (XXY); causing a range of female-like changes to a male orientated body e.g. development of breasts, wide hips, long legs, etc.
what chromosome number does trisomy form for Down syndrome
21
what are some of the features of Down syndrome
growth failure, mental retardation, flat back of the head, abnormal ears, palm crease, special skin ridges and many more
name two other trisomy genetic disorders
Edwards syndrome - trisomy 18
Patau’s syndrome - trisomy 13
name 3 major genetic diseases (not disorders)
- Cystic fibrosis
- Tay-Sachs disease
- Sickle cell anaemia
what causes cystic fibrosis and what are some of the side effects of it
caused by a defective protein in cell membrane - causes thick mucus formation in the lunges and digestive tract
