Ch 3- Genetics Flashcards
How many genes does the human genome contain? On how many pairs of chromosomes?
30 000-80 000 genes on 23 pairs of chromosomes
Basic genetic material formed by pairs of nucleotides
DNA
For each pair of chromosomes, genes for the same trait in the same location (eye colour or nose shape)
Alleles
A process with body cells by which 2 identical cells are produced
- Mitosis
What is meiosis?
- A process by which 4 cells are produced, with each containing only 23 chromosomes called gamates (sperm or ova that will combine at conception to form a new individual)
Crossing over occurs during _____
- Meiosis
True or false: crossing over virtually assured that no 2 ppl (except identical twins) will ever have exactly the same genes
- True
________ established that certain traits are transmitted from parent to offspring
Mendel
What does the principle of dominance state?
- Some genes are always expressed (dominant) others are recessive
The expressed trait is the?
- Phenotype
What is the genotype?
- The underlying genes that govern the train
Brown eyes, dark hair & normal colour vision are ______ traits, expressed in the _________.
- Dominant
- Phenotype
What are some recessive traits? When are they expressed in the phenotype?
- Blue eyes, baldness, colour blindness
- Expressed when paired with another recessive gene
What is the difference between homozygous alleles and heterozygous alleles (single gene inheritance)?
- Homozygous alleles: parents have contributed similar genes for a trait (BB,bb)
- Heterozygous alleles: parents have contributed different versions. Phenotype of child often determined by dominance
When traits are determined by a number of genes (I.e height, weight) this is known as _________ inheritance
- Ploygenic
When the dominant gene does not completely suppress the recessive gene- it blends, this is called
- Incomplete dominance
What is co- dominance?
- When both genes are dominant and thus, both expressed in phenotype ex: blood type- dad has A, mom has B, child will get both
Inherited disorders and chromosomal abnormalities are examples of ________ disorders
- Genetic
Inherited disorders can result from both ______ and _______ alleles
- Dominant
- Recessive
How can chromosomal abnormalities result?
- Myotic division
- Teratogens
This dominant, hereditary disorder is characterized by nervous system degeneration, uncontrollable muscle movements, and death. It is a result of an abnormality of chromosome 4
- Huntington’s disease
What are some characteristics of PKU?
- Inability to metabolize the amino acid phenylalanine due to lack of liver enzyme (toxic in CNS), intellectual disability, periodic convulsions & seizures may occur
- ppl with this are put on a low- protein diet
- screened at birth and 2 weeks post birth
This is a fatal nervous system disease in which the body cannot metabolize fats very well due to the absence of the enzyme hexosomindase
- it effects chromosome 15
- Tay- Sachs disease
This refers to the compete set of genes that an organism processes
Genome
