Chapter 13 Flashcards
Define genome
An organisms complete set of DNA. Includes all genes needed to build and maintain an organism
What is the human genome project
A research project in 1990 that studied the sequences of base pairs and aimed to map all human genes
What does is mean if a genome is sequenced
The precise order or sequence of bases in the DNA of a genome has been identified
Two facts about genomes
Every persons apart from twins has a unique genome
The genomes of two unrelated people are 99.9 per cent the same
Differences between chromosome 22,21 and 1
22- first human chromosome to be sequenced (1999)
- has 51 million bases and 431 genes
21- 48 million masses and 225 genes
1- largest human chromosome, 250 million bases and 2100 genes
5 Benefits of the human genome project
Diagnosis- improved and more accurate diagnosis of inherited disease
Treatment- understand how mutant alleys produce undesirable effects. Help generate new treatments
Prevention- identify people who are at risk of disease eg stroke or cancer
Human biology- better understanding of human development
Human evolution- after mapping all organisms we can see how they are related
What is single nucleotide polymorphism
There is just a single base difference in one strand of DNA
Protein coding genes
Genes on a chromosome that are transcribed into messenger RNA
Ribosomal RNA
the RNA molecule that forms part of the ribosomes
Transfer RNA
The RNA molecule that is involved in synthesis of proteins in a cells
Non coding DNA
a DNA molecule that is part of the human genome
Promoter and enhancers
A regulatory elements that govern when a gene is active and its level of expressions
Structure of DNA
Double helix shape
Base pairs inside
Phosphate and sugar edges
Define dissociation
When the hydrogen bonds break as enzymes unwind molecule
Define DNA polymerase
When new nucleotides joined together by enzymes
DNA replication steps
Unwinding- dissociation,
Pairing- complementary base pairs occurs
Joining- new nucleotides join together, each double helix contains one new strand and one original strand
What is chargaffs rule
The proportion of A and T are about equal and also are the proportions of C and G
Two scientist that are given credit for discovering the structure of DNA
James Watson and Francis crick
What two bases are purine and how many rings
Adenine and guanine and two rings
What two bases are pyrimidines and how many rings
Cytosine and thymine and one ring
How many hydrogen bonds does each base pair have
A-T has 2 hydrogen bonds
C-G has 3 hydrogen bonds
What are mendels three laws
Law of segregation
Law of dominance
Law of independent assortment
Law of segregation
States that Allele pairs separate randomly during the formation of gametes. The member of each pair of factors separate into different gametes with one factor per gamete
Law of dominance
States that one of the factors for a pair of inherited traits will dominate and the other recessive
Law of independent assortment
States that alleles of one gene sort into gametes independently of the alleles of another gene
Eg tall gene does not affect colour gene
Why did Mendel chose peas
Fast growing
7 visible traits eg short/Tall, seed colour, round/wrinkles, pod colour, flower colour, pod texture, terminal/axial
Was mendels experiment praised.
It was ignored until rediscovered by scientists in 1900
What did Griffiths discover
Genetic material is a chemical substance
What did averys experiments show
Provided evidence that the genetic material was composed of DNA
What is the number of human genes
21000
What did Mendel hope to achieve
To understand inheritance of variation by artificially crossing pea plants
How are genes named
After the functions they control
Where are genes located in cells
Almost all human genes are present in the DNA of the cell nucleus
Each gamete contains haploid human genome
Define histones
The proteins that DNA double helix becomes tightly coiled around
How do genes differ
Different genes have a different base sequence
Define genotype
The alleles an individual inherits
Define phenotype
The observable characteristics
Hybridisation
Pairing of complementary DNA chains from different sources
Define kinetichore
A structure that surrounds the centromere where the spindle fibres attach
Define telomeres
Chromosome ends
