B14 - Variation and Evolution Flashcards
What do genomes code for?
An entire organism
What was Charles Darwin’s idea of ‘survival of the fittest’
Natural selection as the fittest individuals would survive and reproduce
Charles Darwin’s theory of natural selection took a long time to be accepted. As of now, it has been proven lots of times.
What are some examples it has been proven?
Development of antibiotic resistance in bacteria
Fossil records
Why do all multicellular, eukaryotic organisms require a continuous supply of new cells?
For growth, development and repair
What are the three main stages of the cell cycle?
Growth
DNA replication + mitosis
Division
Why do we call gametes haploid cells?
Because they have half the genetic material of a normal cell
What are diploid cells?
Cells that contain two sets of genetic information (one from each parent)
What are maternal chromosomes?
Chromosomes from the mother
What are paternal chromosomes?
Chromosomes from the father
What is the first step of meiosis?
The cells replicates all its DNA
The chromosomes line up into 23 pairs and then divides into 2 daughter cells
What shape does the original and replicated chromosome make?
They form a symmetrical X-shape
Why is the DNA different in each cell divided by meiosis?
The left to right order is random so there is trillions and trillions of combinations
What is the second step of meiosis?
The chromosomes line up along the centre of the cell
The opposite symmetrical arms of each chromosome are pulled to each side of the cell to divide again
This creates 4 daughter cells
How many chromosomes does each daughter cell have after the first division
23 chromosomes each
How many chromosomes does each daughter cell have after the second division?
23 chromosomes again
What is different about the 4 daughter cells from one cell in meiosis?
They are all genetically unique
What can we call the 4 genetically unique daughter cells in meiosis?
Gametes
What are the two main ways organisms can reproduce?
Sexual reproduction
Asexual reproduction
What is fertilisation in terms of gametes?
The fusion of male and female gametes
When plants reproduce with the fusion of Egg cells and Pollen cells, is it sexual or asexual reproduction?
Sexual reproduction
In asexual reproduction, all the offspring are _______
Identical
How do eukaryotic organisms (like plants, fungi and few animals) asexually reproduce?
Through mitosis
How do prokaryotic organisms (like bacteria) asexually reproduce?
Binary fission
What are the main benefits of asexual reproduction?
- Only one parent is needed
- process is very quick
Only one parent is needed for asexual reproduction and the process is very fast. Why would this be a benefit?
It allows a single organism to quickly colonise a new area
What are the drawbacks of asexual reproduction?
- no genetic variation
- less chance or adapting to new conditions
Why is no genetic variation a drawback for asexual reproduction?
Reduced gene pool would mean when theres a disease, theres a high risk all offspring could die
What is the main advantage of sexual reproduction?
Lead to high genetic variation
What are the short term and long term benefits of sexual reproduction allowing genetic variation?
Short term: population is less likely to get wiped out by a new disease
Long term: allows evolution - the population can adapt to changing conditions
What is the main disadvantage of sexual reproduction?
Takes more time and energy for the animals to impress and find their mate
What are the steps you should follow when drawing a genetic diagram?
Parents Phenotype
Parents Genotype
Gametes Genotype
Punnet Square
Offsprings Genotype
Offsprings Phenotype
What is embryo screening?
Testing embryos from IVF to see if they have inherited genetic disorders
What are the pros of embryo screening?
- helps prevent the suffering of the offspring
- saves money on treating the offspring’s disorder
What are the cons of embryo screening?
- Implies people with genetic disorders are not wanted
- in the future, people can start screen for other traits like eye colour, physique and gender
What is selective breeding?
Where you take the best plants/animals in a population and breed them together in the hope of getting a desired offspring
How long has selective breeding been a method farmers used?
For 1000’s of years
What are the disadvantages of selective breeding?
It reduces the gene pool of the population which leads to inherited disorders and higher risk of diseases
Less variation which could lead to a wipe out from disease
What is genetic engineering?
Taking a gene from an organism with a desirable characteristic and transfer it to another organism
Whats another way of saying genetic engineering?
Genetically modifying
What are the pros of genetically modified crops?
More fuits
Resistant to disease
Produce special nutrients for developing countries
What are the cons of genetically modified crops?
We don’t know for certain if they affect our health
These better plants could outcompete other plants and completely change the ecosystem
How do we actually transfer a gene from one organism to another? (genetic engineering)
Find the gene you want and cut the section of DNA out using enzymes
Insert the gene into a vector like a virus and introduce it to the organism
The organism willb start producing the same proteins and take on the characteristic
What is tissue culture?
When cells are grown into a new organism
Describe how you would carry out selective breeding.
Seclect your two best organisms with the best desirebale characteristics.
Breed them together in hopes of getting offspring with even better characteritsics.
Breed the offspring together and then repeat this for generations to come
