Topic 6 – Inheritance, Variation and Evolution Flashcards
What is the variation?
differences in the characteristics of individuals in a population
What can cause variation?
genetic causes, environmental causes, and a combination of genes and the environment
How do new phenotype variants occur?
mutations
What is selective breeding?
breeding plants and animals for particular characteristics
Describe the process of selective breeding.
- choose parents with the desired characteristic
- breed them together
- choose offspring with the desired characteristic
- continue over many generations until all offspring show the desired characteristic
What are the consequences of inbreeding?
inherited defects and disease
What is genetic engineering?
modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic
How have plant crops been genetically engineered?
to be resistant to disease/herbicides/pesticides, to produce bigger fruits, to give higher yields
How have bacteria been genetically engineered?
to produce useful substances, such as human insulin to treat diabetes
What are enzymes used for in genetic engineering?
cut out the required gene
What is used to transfer the required gene into the new cell in genetic engineering?
vector( e.g., bacterial plasmid or virus)
Describe the steps involved in adult cell cloning
- nucleus removed from an unfertilised egg cell
- nucleus from an adult body cell inserted into a cell
- electric shock stimulates egg cells to divide to form an embryo
- embryo develops and is inserted into the womb of an adult female
What is tissue culture cloning?
using small groups of cells from plants to grow identical new plants
Why is tissue culture cloning of plants important?
preserve rare species and for growing plants commercially in nurseries
What is cutting as a cloning method?
simple method used by gardeners to produce many identical plants from a parent plant
Describe cloning through using embryo transplants.
cells split apart from a developing animal embryo before they are specialised, then the identical embryos are transplanted into host mothers
What is sexual reproduction?
joining(fusion) of male and female gametes
What type of cell division is involved in sexual reproduction?
meiosis
What type of cell division is involved in asexual reproduction?
mitosis
What is meiosis?
cell division that produces four daughter cells (gametes), each with a single set of chromosomes
What are the male and female sex chromosomes in humans?
XX-female, XY-male
How can plants produce asexually?
bulb division (e.g.,daffodils) or runners (e.g.,strawberry plants)
What is the genetic material in cells called?
DNA
What is DNA?
polymer made of chains of four different nucleotides
What does a nucleotides consist of?
sugar, phosphate group, and one of four different bases (A, G, C, or T)
What is the structure of DNA?
two complementary strands of nucleotides forming a double helix
What is a gene?
small section of DNA that codes for a particular amino acid sequence, to make a specific protein
How many bases code for an amino acid?
three
Which bases pair in complementary DNA strands?
C with G, T with A
What is the function of non-coding DNA?
switch genes on and off to control their expression
What are alleles?
different forms of the same gene
What is recessive allele?
allele that needs to be present twice to be expressed
What is a dominant allele?
allele that is always expressed, even if only one copy is present
What is a genome?
the entire genetic material of an organism
Define the term homozygous.
two of the same alleles present in an organism
Define the term heterozygous.
two different alleles present in an organism
Where in the cell are protein made?
on the ribosomes
What type of allele causes polydactyly?
dominant allele
What type of allele causes cystic fibrosis?
recessive allele
How many chromosomes do normal human body cells have?
23 pairs
What is evolution?
change in the inherited characteristics of a population over time through natural selection
Who first proposed the theory of evolution by natural selection?
Charles Darwin
What is the theory of evolution by natural selection?
all species of living things evolved from a common ancestor that developed billions of years ago
Describe Lamarck’s idea of inheritance.
organisms change over their lifetimes and these characteristics can be inherited
Why was the theory of evolution by natural selection controversial?
- challenged the idea that God made all of Earth’s animals and plants
- insufficient evidence at the time
- genes, inheritance, and variation were not understood
What is speciation?
gradual formation of a new species as a result of evolution
What evidence supports the theory of evolution?
- parents pass their characteristics to offspring in genes
- fossil record evidence
- evolution of an antibiotic-resistant bacteria
What did Mendel discover through breeding experiments on plants?
inheritance of characteristics is determined by units (genes) passed on unchanged to offspring
What are fossils?
remains of organisms from millions of years ago, found in rocks
How might fossils be formed?
- parts of an organism do not decay because the conditions needed for decay are absent
- traces of organisms are preserved
- parts of an organism are replaced by minerals
What are the problems with the fossil record?
- many early organisms were soft-bodied so left few fossils
- gaps in the fossil record as not all fossils have been found and some have been destroyed
What are the benefits of the fossil record?
can learn how species changed and life developed on Earth, and can track movement of species across the world
What is extinction?
no individuals of a species are still alive
What is the binomial system?
naming of organisms by their genus and a species
What classification system did Carl Woese introduce?
three-domain system of Archaea, Bacteria, and Eukaryota
Why can bacteria evolve rapidly?
they reproduce at a fast rate
How do antibiotic-resistant strains of bacteria develop?
mutations that allow the strain to survive and reproduce
