Chapter 10 - Genetics Flashcards
What is the genome ?
The entire genetic material of an organism
Describe the arrangement of genes in a chromosome and where are they found ?
they are arranged in functional pairs, found in every nuclei in the body
What are the only two types of cells where the genes are not organised in the typical way ?
- gametes
- bacteria
What is a gene ?
Short sections of chromosomes the code for a particular characteristic
What is an allele ?
One of two possible versions of a particular gene
What does DNA consist of ?
- phosphate
- sugar backbone
- base pairings
Describe the structure of DNA
In a double helix shape.
What are the two base pairings and their rules ?
A - T
C- G
each base can only link with the other base in their pair
How does DNA code for a particular characteristic ?
The arrangement of the base pairings produces particular amino acid, a long string of amino acids will create a protein needed.
What is a base triplet ?
A sequence of three bases in DNA that codes for a particular amino acid
What does mitosis allow the body to do ?
- grow
- replace worn out cells
- repair damaged tissue
What is mitosis ?
Cell division that produces genetically identical (daughter cells ) to the parent cell and to each other
What sort of division is Meiosis
reduction division
What are the products of meiosis ?
4 genetically different haploid daughter cells
Why are the daughter cells genetically different in meiosis ?
The random independent assortment of chromosomes gives a unique gamete, producing variation in offspring
What are test crosses used to determine ?
an unknown genotype
What does homozygous mean ?
the alleles are the same
What does heterozygous mean ?
the alleles are different
How is sex determined in humans ?
Humans have 1 pair os sex chromosomes. A sex chromosome can either be X or Y.
Male = XY Female = XX
How is each sex chromosome allocated to the person ?
During meiosis the female provides one and the male provides one. Half the males sperm will be X and half Y. All the females eggs will have an X chromosome.
Name 4 diseases that can be genetically inherited
- haemophilia
- cystic fibrosis
- huntingtons
- downs syndrome
Describe how the genetic inheritance genetic diseases occurs.
haemophilia - sex linked, caused by a receive allele on the x chromosome
cystic fibrosis - caused by a recessive allele so individuals must be homozygous recessive
huntingtons - it is caused by the presence of a dominant allele
downs syndrome - caused by having an extra chromosome 21
What are the (dis)advantages of amniocentesis ?
Advantages :
- can show if the baby will be born with a genetic condition
Disadvantages :
- carries the risk of miscarriage (about 1%)
What are some ethical argument against genetic screening ?
- who decides who can be tested
- risks of failure
- dilemma for carries of the disease
