B2 - Inheritance Flashcards
How do body cells divide?
Body cells divide by mitosis and meiosis.
How is genetic information carried?
Genetic information is carried as genes on chromosomes.
Why is there no variation in offspring produced by asexual reproduction?
The offspring is produced by mitosis so they all contain the same alleles as the parent cell.
What are sex cells called?
Sex cells are called gametes.
How are gametes produced?
Gametes are produced when the cells in the sex organs divide by meiosis. Sex cells have only one set of chromosomes.
Why do gametes only have one set of chromosomes (23)?
A human body cell contains 46 chromosomes. The parent cell chromosomes make identical copies of themselves, they divide so you have 2 pairs of cells with 46 chromosomes that divide again to form 4 genetically different gametes with 23 chromosomes each. Meiosis reduces the chromosome number.
Why does sexual reproduction result in variety?
Two organisms with different genetic makeup produce an offspring that is a combination of the two different genotypes, this creates a genetically unique individual.
What is the source of stem cells in humans?
In humans, stem cells are usually found in bone marrow.
Describe the differences between plant and animal cells.
A plant cell is usually bigger in size, cannot change shape and has a cell wall protecting the inside of the cell.
Explain the function of stem cells.
Stem cells are undifferentiated cells in a developing fetus. They are researched to see if stem cells can be used to repair damaged parts of the human body, instead of having to use transplant organs
How could stem cells be used to treat medical conditions?
Stem cells could be used as an alternative to organ transplants. For example in spinal cord injuries, stem cells can be coerced into becoming nerve cells.
What are the social and ethical issues in the use of stem cells from embryos?
Many embryonic stem cells come from aborted embryos. Many religious groups feel this wrong as the embryo is a potential human being and is a violation of human rights.
What is a gene?
A gene is a small section of DNA.
What does each gene code?
Each gene codes for a particular sequence of amino acids to make a specific protein.
Describe some of the experiments carried out by Mendel using pea plants.
Mendel used breeding experiments of pea plants and used different types (smooth, wrinkly, green and yellow) by cross breeding them and predicting the offspring’s appearance.
Why did Mendel propose the idea is separately inherited factors?
Mendel realised that some characteristics with dominant over others and that they never mixed together.
Why did no one recognise Mendel’s discovery until after his death?
No one recognised Mendel’s discovery until after his death because there was no way of explaining chromosomes and people didn’t understand his theories.
What is the definition of homozygous?
Homozygous means you’ve got a pair of matching alleles, which are the two genes that control a particular trait.
What is the definition of heterozygous?
Heterozygous refers to a pair of genes where one is dominant and one is recessive — they’re different.
What is the definition of phenotype?
The phenotype is the physical appearance of an organism as distinguished from its genetic makeup.
What is the definition of genotype?
The definition of genotype is the internally coded, inheritable information carried by all living organisms.
What is the definition of DNA fingerprinting?
The definition of DNA fingerprinting is using samples of the body in order to identify individuals.
What is a polydactyly?
Polydactyly is the time to describe extra fingers on the hands or extra toes on the feet.
How is polydactyly inherited?
Polydactyly is caused by a dominant allele of a polydactyly gene.
