Simple Inheritance In Animals And Plants Flashcards
Why we new cells needed for an organism?
To replace cells which become worn out and replace damaged cells
Where is DNA in your cells found?
Nucleus and Mitochondria
What is a gene?
A gene is a small packet of information that controls a characteristic or part of a characteristic, of your body.
What is an allele?
A different version of the same gene which can be either recessive or dominant
What is a recessive gene?
A recessive allele needs two allele to be expressed
What is a dominant gene?
A dominant allele only needs one allele to be expressed
What is a gamete?
The sex cells
How many chromosomes in human body cells?
23 pairs or 46 chromosomes
What are the products of Mitosis?
Mitosis results in two identical cells being produced from the original cell
What do chromosomes contain?
Genes (alleles) which must be passed onto the new cell
What must happen before the cell divides?
A copy of each chromosome is made and one of each chromosome goes to each cell
What are stem cells?
Unspecialised cells
How are plant cells different to animal cells?(differentiation)
Most animal cells differentiate early in development but plant cells can differentiate throughout their life.
How are cells of offspring produced by asexual reproduction?
Mitosis from the parent cell. They contain the same allele as the parents
What happens in mitosis after the chromosomes have been copied?
The chromosomes line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosome go to opposite ends of the cell.
Membranes then form around each of the sets of chromosomes. These become the nuclei of the two cells.
Then the cytoplasm divides
How are sex cells (gametes) formed?
Cells in reproductive organs e.g. Testes and ovaries divide by meiosis. The gametes in humans are sperm and ova
How many chromosomes do gametes have?
Each gamete has only one chromosome from each original pair (only 23)
How does sexual reproduction result in variation?
This is because the gametes from each parent fuse. So half the genetic information comes from the father and half from the mother
What is formed when gametes join at fertilisation?
A single body cell with new pairs of chromosomes. A new individual is then developed by their cell repeatedly dividing by mitosis
What happens in Meiosis?
Before division, a copy of each chromosome is made. Then the chromosome pairs line up in the centre of the cell.
The pairs are pulled apart so each new cell only has one copy of each chromosome.
The second division is a lot like mitosis, as the chromosomes again line up in the middles
This form four gametes.
Where are stem cells found?
In human embryos and in adult one marrow
What is differentiation?
This is when cells become specialised for a particular function
What does DNA stand for?
Deoxyribonucleic Acid
What is the hoped result of stem cell research?
The stem cells can be made to differentiate into many types of cell. The cells formed can be used to treat conditions such as paralysis, e.g by differentiating into new nerve cells
Which scientist worked out how characteristics are inherited?
Gregor Mendel
What did Gregor Mendel call what we now call genes?
Factors
Why did it take a long time for Mendel’s ideas to be accepted?
Because scientists didn’t know about genes and chromosomes at the time
What are chromosomes made of?
DNA which is a very long molecule with a double helix structure
Who doesn’t have different DNA?
Identical Twins and clones
What does a gene code for?
A particular combination of amino acids which make a specific protein.
What is the combination of sex chromosomes in Females?
XX
What is the combination of sex chromosomes in males?
XY
What does Heterozygous mean?
The alleles are different e.g Dd, Bb
What does homozygous mean?
The alleles are the same e.g dd, DD
What is phenotype?
The physical appearance of the characteristic expressed e.g dimples, eye colour
What is genotype?
The genetic make up e.g DD, Dd
What is an example of a dominant allele that is a genetic disorder?
Polydactyl where a baby is born with extra fingers or toes
What is an example of a recessive allele that is a genetic disorder?
The Cystic Fibrosis allele affects the cell membranes and causes the production of a thick sticky mucus. This can affect several organs
What is the word to describe the parents who pass on the allele but might not have it expressed in their own body?
Carrier
What chance is there for the offspring to polydactyl if a parent is heterozygous for polydactyl?
50%
If both parents are heterozygous for cystic fibrosis, what are the chances that the child will inherit the disorder?
25%
How can you show the outcomes of genetic crosses?
A Punnet square
Where are embryonic stem cells taken from?
IVF
Created Adult cells
Umbilical cord of newborn babies
