Genetics (Chapters 15-19) Flashcards
Species
A species is a group of similar organisms that are capable of naturally interbreeding with each other to produce fertile offspring.
Variation within species
Variation within species means that in a group of successfully interbreeding organisms the individual members show different characteristics.
Classification
Classification is placing organisms into similar groups according to similarities in structure, function and development
Acquired Variation
These are not inherited.
Inherited Variation
These are inherited
Heredity (genetic inheritance)
Heredity is the passing on of features from parents to offspring by means of genes.
Genes
A gene is a section of DNA that causes the production of protein.
Gene expression
Gene expression is the precise way in which the genetic information in a gene is decoded in the cell and used to make a protein
characterists = ______+______
heredity + environment
Chromosomes are composed of about 60% _______ and 40% _________
Chromosomes are composed of about 60% protein (called histone) and 40% DNA
___% of DNA in a human cell does not consist of genes. This DNA is said to be non-coding DNA
97%
________ are responsible for holding the DNA in its folded state
Proteins are responsible for holding the DNA in its folded state.
The strands are linked by pairs of chemicals, called _____
bases.
Name the four bases.
adenine (A)
thymine (T)
guanine (G)
cytosine (C)
What base does adenine join with?
Thymine
What base does guanine join with?
Cytosine
A chromosome consists of many base pairs arranged into a _____________
double helix.
Genes are made of ___
DNA
A gene is a section of DNA required for the production of _____________
a particular protein molecule.
DNA codes for each amino acid by using a sequence of three consecutive bases called ________
a codon.
DNA profiling
DNA profiling is a method of making a unique pattern of bands from the DNA of a person, which can be used to distinguish that DNA from other DNA.
1st step in Preparing a DNA profile
DNA is released by the breakdown of cells
2nd step in Preparing a DNA profile
The DNA is cut into fragments using special enzymes called restriction enzymes
3rd step in Preparing a DNA profile
The fragments are separated on the basis of their sizes. Separated by a process called gel electrophoresis.
Process of electrophoresis.
DNA fragments placed in a small glass tank containing a sugar based gel. Electric current is applied along the gel. The current draws the negatively charged DNA to one end of the gel. Small DNA fragments move faster to the porous gel than do the larger fragments. In this way bands of small fragments are separated from bands of larger fragments.
4th step in Preparing a DNA profile
Patterns are compared.
Application of DNA profiles
- Crime- to see if someone was present at a crime scene
2. Medical- to determine paternity or maternity of a child.
Genetic screening
Genetic screening means testing DNA for the presence or absence of a particular gene
What are the bases of RNA
Adenine, guanine, cytosine and uracil
What base does adenine join with?
Uracil
RNA is a __________ molecule unlike DNA
Single stranded
DNA sequence GGAATC. What will be the RNA sequence?
CCUUAG
Where is RNA found?
In the nucleus and the cytoplasm. Unlike DNA, RNA can move out of the nucleus
Transcription
Transcription is the copying of a sequence of genetic bases from DNA onto messenger RNA (mRNA)
Translation
Translation is the conversion of a sequence of genetic bases on messenger RNA into a sequence of amino acids
Purine bases
Adenine
Guanine
Pyrimidine bases
Thymine and cytosine
Difference between purine and pyrimidine bases
Purine bases are double ringed molecules and pyrimidine are single ringed molecules
Three parts of a nucleotide
Phosphate, sugar and nitrogen base (eg A,T,C or G)
DNA is made up of units called ______________
Nucleotides
The nucleotides join together, with a bond between the phosphate group of one and the sugar group of the next forming a ____________
Polynucleotide
The forces holding the bases together are _______________
Hydrogen bonds
Gametes
Gametes are haploid cells that are capable of fusion
Fertilisation
Fertilisation is the Union of two gametes to form a single cell called a zygote
Alleles
Alleles are different forms of the same gene
Locus
The locus of a gene is its position on a chromosome.
Dominant
Dominant means that the allele prevents the working of the recessive allele.
Recessive
Recessive means the allele is prevented from working by a dominant allele
Genotype
Genotype means the genetic make-up of an organism
Phenotype
Phenotype means the physical make-up of an organism
phenotype = ________+________
environment + Genotype.
Progeny
Progeny refers to offspring that are produces
Homozygous
Homozygous means that two alleles are the same
Heterozygous
Heterozygous means that the alleles are different.
Incomplete dominance
Incomplete dominance means that neither allele is dominant or recessive with respect to the other. both alleles work in the heterozygous genotype to produce an intermediate phenotype.
What is the name of the first 44 chromosomes?
autosomes
What are the last two chromosomes?
sex chromosomes
What letters represent a female?
XX
What letters represent a male?
XY
In which species are the patters of sex determination reversed
Birds, Butterflies and Moths. The males are XX and the females are XY
Who is known as the father of genetics?
Gregor Mendel
What is the law of segregation?
It states that Inherited characteristics are controlled by pairs of factors. These factors segregate from each other at gamete formation, with only one member of the pair being found in each gamete.
What is the law of independent assortment?
It states that when gametes are formed, either of a pair of factors is equally likely to combine with either of another pair of factors.
Linkage
Linkage means that genes are located on the same chromosome.
Sex linkage
Sex linkage means that a characteristic is controlled by a gene on an X chromosome.
Example of a sex linked characteristic?
Colour-blindness.
Non-nuclear inheritance is found where?
In chloroplasts and mitochondria
Non-nuclear DNA is passed on only from the (____ male/female____)?
female
What does non-nuclear DNA allow?
It allows organelles to reproduce independently of the cell.
Mutation
A mutation is a change in the amount or structure of DNA
Mutagens
Mutagens are agents that cause mutations
Gene (or Point) mutations
Gene mutations are changes in a single gene
Example of a gene mutation
Sickle Cell Anaemia
Chromosome mutations
Chromosome mutations are large changes in the structure or number of one or more chromosome.
Example of a chromosome mutation
Down’s Syndrome
Evolution
Evolution is the way in which living things change genetically to produce new forms of life over long periods of time.
Natural Selection
Natural selection is the process by which those organisms with genetically controlled characteristics, that allow them to be well adapted to their environments, will survive and reproduce to pass on their genes to following generations.
Evidence of evolution?
Fossils
Study of fossils?
Palaentology
Fossil
A fossil is the remains of (or is produced by) an ancient organism
Fossils can be formed as (x5)
- entire organisms
- preserved parts
- seeds
- pollen grains
- imprints
Genetic Engineering
Genetic engineering is the artificial manipulation or alteration of genes.
