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Flashcards in Lecture 7 Deck (23):
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What are mendelian traits?

Discrete phenotypic character differences generally determined by a single gene difference

1

What are complex traits?

Phenotypes which vary over a continuous range and are usually mutigenic. They normally show normal distribution.

2

What are the three causes of continuous variation of a character?

Genetic
Environmental
Genotype-environment interaction

3

What is the basis of the additive model of polygenic inheritance?

Two unlinked genes contribute to give a variety of possible phenotypes

4

What is a karyotype?

The complete set of chromosomes in a cell

5

What are autosomes?

Chromosomes which are not involved in sex determination

6

How did scientists come to a conclusion that the human karyotype contained 22 autosomes and 1 sex chromosome?

In 1952 a technician used distilled water instead of saline water for washing the cells. This hypotonic treatment allowed seperatuon before squashing

7

What is colchicine used for?

It arrests the chromosomes at mitotic metaphase

8

What is the Denver system?

A method of organising the genome into 7 groups, organised by size and relative centromere position

9

What is G banding?

A karyogram of human male using Giemsa staining: about 400 bands per haploid set

10

What is Q banding?

Uses quinacrine mustard creates bands on the chromosomes which allow them to be mapped into regions which allows the chromosomes to be accurately identified

11

What is FISH?

Flourescent in-situ hybridization otherwise known as chromosome painting. It enables each chromosome to be uniquely visualised

12

What are Idiograms?

Divided into bands and sub-bands, comes from both G and Q banding

13

What are pseudoautosomal regions?

Genes located within PAR1 & 2 are inherited just like any autosomal genes. They escape X inactivation and are therefore candidates for having gene dosage effects in sex chromosomes aneuploidy conditions.

14

What is SRY?

The sex-determining gene on the Y chromosomeshich encodes the testis determining factor

15

Give 3 examples of sex linked traits in humans

Haemophilia
Duchenne Muscular Dystrophy
Lesch-Nyan syndrome
Red-green colour blindness

16

How can we track parental inheritance on the maternal side?

By looking at mitochondrial DNA as this is cytoplasmic

17

What are Barr bodies?

Condensed X-chromosome which is genetically silent, inactivation occurs early in embryonic development

18

What is aneuploidy?

Loss or gain of one chromosome

19

What isa polyploidy?

More than 2 complete sets of chromosomes

20

What is allopolyploidy?

Two or more sets of genetically distinct chromosomes

21

What is down syndrome?

Trisomy on chromosome 21

22

How was modern bread wheat made?

Cross 1: about 8000 BC
Einkorn wheat (AA) x wild grass (BB) = Emmer Wheat (AABB)
Cross 2: about 6000 B
Emmer wheat (AABB) x wild grass (DD)= bread wheat (AABBDD)