Inheritance Flashcards
What is the chemical which makes up your genes?
DNA
Deoxyribose nuclic Acid
What is genetics?
Study of your genes and how you inherit them from your parents
What are small sections of DNA called?
Genes, which are then made up into chromosomes
How many chromosomes are in the average human body?
46 chromosomes and 23 pairs.
Using knowledge of genetics, what does it enable us to do?
Predict what type if OFFSPRING the parent may produce
What are the two forms of gene and explain them?
Dominant; you only need one copy for you to see the characteristic in the person.
Recessive; you need 2 copies for youth see that characteristic.
What division divides chromosomes to get gametes?
Meiosis
What is a phenotype?
The characteristic that you see
What does Heterozygous mean?
When the genes are dominant
e.g. Bb or BB
What does Homozygous mean?
Genes are recessive
e.g. bb
What does the nucleus contain?
Genetic material in the firm of chromosomes
What does a DNA molecule look like?
Two strands coiled together in the shape of a double helix (two spirals)
What is Asexual reproduction in humans?
- one parent involved
- offspring have identical genes to the parent
- no variation between patent and offspring
What is Mitosis?
“Mitosis is when a cell reproduces itself by splitting, to form two cells with identical sets of chromosomes”
What are the 5 steps of mitosis?
- ) signal to divide, cell duplicates it’s DNA (one copy for each new cell) X-shaped chromosomes formed.
- ) chromosomes line up at centre of cell and fibres pull them apart. Each go to opposite end of the cell.
- ) membranes form around each chromosome. These become the nuclei of the new cells
- ) cytoplasm divides
- ) two new cells, sane DNA, genetically identical.
What does meiosis involve?
4 non identical haploid cells.
What is sexual reproduction (in terms of cells) ?
Genetic information from two organisms (mum and dad) is combines to produce offspring which are GENETICALLY DIFFERENT.
What are the two gametes in sexual reproduction and who makes them?
- mum and dad
- egg cells and Soren cells
how many chromosomes does each gamete contain?
23 chromosomes
So the haploid number is 23.
What is fertilisation?
Make gamete fuses with a female gamete to form a zygote (fertilised egg) the zygote ends up with the full set of chromosomes.
What happens after the zygote undergoes cell division?
It develops into an Embryo.
How is genetic variation random?
The fertilisation of gametes is random.
What are the four steps in the first division of MEIOSIS?
- ) cell duplicates it’s DNA (1 arm of each chromosome is an exact copy of the other arm
- ) chromosomes line up in pairs in the centre of the cell
- ) the pairs then get pulled apart and each cell gets one copy of each chromosome.
- ) each new cell gets a mixture of mum and dad’s genes.
What are the two steps in decision 2 of meiosis?
5.) Again the chromosomes line up in the centre of the cell.
Arms of the chromosomes are pulled apart.
6.) 4 haploid gametes are produced each with a single set of chromosomes and genetically different
