S Inheritance And Variation Flashcards
sexual reproduction definition
Sexual reproduction involves two parents where the Male and female gametes join together to form a zygote
What happens in sexual reproduction
Genetic information from 2 different individuals combines together during fertillsation to produce offspring
asexual reproduction definition
Involves one parent with the offspring having identical genetic information to the parent
Which has greater variation? Asexual or sexual offspring?
The offspring produced by sexual reproduction show much greater variation than the offspring produced by asexual reproduction
Example of asexual reproduction
Strawberry plants, onions, potato plants
When does asexual reproduction occur
Occurs in one-celled organisms called amoeba
variation definition
The way members of the same species differ is known as variation
What is responsible for variation
Changes in DNA are responsible for variation, these changes are called mutations
species definition
A species is a group of organisms that can breed with each other and produce fertile offspring
fertile definition
Means that an organism is capable of producing young
What is the shape of DNA called and what is it made of
A double helix and it is made of sugar and phosphates
What are the steps in the helix of DNA called?
They are called steps
What are the steps of DNA made of
They are made of four bases, Adenine(A), Thymine(T), Guanine(G), Cytosine(C)
chromosomes definition
Chromosomes are made up of lengths of DNA wrapped around protein
How many chromosomes does a Male and female have
They both have 23 pairs
Genes definition
Genes are lengths of DNA along a chromosome. Each gene controls the making of a particular protein
What per cent of DNA in human chromosomes is in the form of Genes and what is the other per cent
Only 3 percent are in the form of Gene’s and the other 97 percent is often referred to as junk DNA because It doesn’t code for anything
How many Gene’s do humans have on their 23 chromosomes
25,000 on their 23 chromosomes
Where are the pairs of Gene’s controlling a particular trait located?
Each gene on a chromosome has a corresponding gene controlling the same trait on the same place on its partner chromosome
How many Gene’s do we have for each trait
2
How does the environment affect characteristics
If an acorn possessed Gene’s to grow tall and strong but was planted in very poor soil it would not grow very well
What did Gregor Mendel discover and what plant did he use to figure this out
Gregor used pea plants and crossed them in order to find a pattern in the inheritance of certain traits
Gregor mendel discovered…
Cells of an organism carry 2 Gene’s for the control of each trait and gametes(sex organs) carry only one factor for each trait
inheritance definition
Inheritance is the way traits are passed from the parents to Offspring
What did mendel mean by factor
What Mendel called Factor is known as Gene
Examples of non inherited traits in human beings
The ability to cycle a bike, play football, speak foreign language
Examples of inherited traits in Humans
Eye colour, hair colour, blood type, earlobes, widow’s peak
What traits in humans are controlled by more than one pair of Gene’s
Eg. Intelligence and height
What is gene expression?
This is when the protein a gene is controlling is actually made
What does genotype mean
Genes an organism possesses for example two genes for brown eyes
What does phenotype mean
The traits that can be seen in the organism
What does dominant mean
A gene that prevents another gene from working (being expressed)
What does recessive mean
A gene that is prevented from being expressed (working)
What are letters used in genetic crosses to denote
They are used to denote Gene’s, dominant genes are given capital letters and recessive genes are given small letters
What does DNA stand for?
DeoxyriboNucleic Acid
