(Module 12) Reproduction Flashcards
What is the cell cycle
This is the process that all body cells use to grow and divide
What are the differences between asexual reproduction and sexual reproduction (Definition wise)
Asexual reproduction only involves mitosis, and is where one cell divides and creates an exact copy of the cell
Sexual reproduction involves a male sex cell and female sex cell, and form a zygote
Factors of sexual reproduction
2 parent cells, gametes (sperm an egg cell, egg cell and pollen), two gametes fuse together, mitosis, variation as dan from two parents
Factors of asexual reproduction
1 parent cell, no gametes, divide by mitosis, no variation of offspring
Factors of Mitosis
Takes place during growth and repair
Takes place in all cells except for gametes
It creates two daughter cells, with the same number of chromosomes
The daughter cells are clones, identical to the parent
Factors of Meiosis
This takes place during the production of gametes (sex cells)
Takes place in reproductive organs
It produces four gametes
The daughter cells have half as many chromosomes
The daughter cells are genetically different from each other and the parent
What is a gamete
This is a sex cell which unites with another sex cell to create a zygote. Contains only one set of chromosomes
Sperm for men, eggs for Women, pollen and seeds for plants
What is DNA
DNA is a chemical found in the nucleus of cells, it is a polymer made up of two strands joined together.
The structure DNA is described as a double - stranded, double - helix molecule. DNA carries our genetic code
What does DNA stand for
Deoxyribonucleic acid (DNA)
What is a Gene
Genes are sections of Chromosomes (DNA) that code for a particular characteristic. Contains a code that codes for a particular sequence (chain) of amino acids
The chains of amino acids make a protein
What are chromosomes
DNA is arranged in long coiled molecules called chromosomes. Each chromosome is composed of DNA and protein molecules (which hold the structure together)
What is an Allele
Each gene has different forms, like different hair colours, and the different forms are called alleles
What is a homozygote and a heterozygote
Homozygote- An individual with two identical alleles for a characteristic, such as BB or bb
Heterozygote- An individual with different alleles for a characteristic, for example Bb
What is a genotype and a phenotype
Genotype- This describes the alleles present or genetic makeup of an individual regarding a particular characteristic, for example Bb or bb
Phenotype- This describes the physical appearance of an individual regarding a particular characteristic, for example black fur or brown fur in a mouse
What are the differences between dominant alleles and recessive alleles
Dominant alleles are the alleles that are expressed/showed, even if there are only one dominant alleles, Bb
Recessive alleles are the alleles that is ‘marked’ by a dominant alleles. Recessive alleles are only expressed if they occur in pairs e.g bb, tt
What is a pungent square
Its the way to work out what percentage there is of a person getting a certain allele
REVISE IT WITH IMAGES
How many chromosomes are there in a normal human body/how many pairs
Extra: how many pairs of chromosomes are for general body characteristics
46 chromosomes, 23 pairs
Extra: There are 22 pairs for general characteristics, whilst the other pair is for what sex you are
What determines the gender in terms of X AND Y, and what is the likelihood
50:50
A female egg cell contains the Allele X
A male sperm cell can have either X or Y
If it is XX, the baby is girl, and if it is XY, it is always a boy
Why would scientists study the Human Genome?
- Search for genes linked to different types of diseases
- Understand and be able to treat inherited diseases
- Used in training human migration patterns from the past
What is Polydactyl and what causes it ?
This is when a baby is born with extra fingers or toes
It is a dominant phenotype caused by a dominant allele
If a parent has polydactyl and are heterozygous, the child has a 50% chance of getting the inherited disorder
What is Cystic Fibrosis and what causes it?
It is a genetic disorder prevents the movement of certain substances from side to the other, which lets cuscus become thick and sticky, clogging up areas like the lungs and the reproductive system
Caused by a recessive allele, so both parents must have it. 25% chance a kid has it
What is an inherited disease
This is a disease that is caused by a result of a change in the coding of our genes passed on by parents to kids
What is genetic screening/testing
This is undergoing tests to discover if a person/embryo/foetus has a genetic disorder or is carrying a faulty allele
How can cells be harvested by embryos to be genetically scanned?
Amniocentesis- takes a sample of the fluid around the baby
Chorionic villus sampling- Sample of tissue surrounding the baby
Analysing foetal cells found in the mothers blood
What are the advantages of Genetic Screening
- Decide whether or not to have children/continue with pregnancy
- Preparation- can plan ahead, and could get treatment for the condition
- They will know if there is a possibility of getting ill in the future
What are the disadvantages of Genetic Screening
- Risk of miscarriage/harm to the mother foetus
- Tests might not be reliable (false positive/false negative) results
- Screening is very expensive
- Ethically or morally wrong in some religion
