B2.5 - Simple Inheritance Flashcards
How are chromosomes arranged in body cells?
Chromosomes are found as pairs.
Why do new cells need identical genetic information?
So the new cells can do the same the job.
Why do cells divide?
To allow growth and the replacement of old and damaged cells.
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What is an allele?
Different forms of the same gene.
How does mitosis take place?
- A cell produces copies of the chromosomes.
- The cell divides to form two genetically identical cells.
Why is cell division restricted in adults?
Most adult cells differentiation has already occurred.
What is a stem cell?
Unspecialised cells.
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How do plant cells differentiate?
- Cells don’t differentiate until in their final position.
- Differentiation isn’t permanent.
- The cell can become a different cell easily.
What is meiosis?
Cell division where the chromosome number is halved.
Why is it easy to clone plants?
- In the right conditions, a plant cell will become unspecialised.
- The cells undergo mitosis.
- The cells differentiate to form a new plant.
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What does meiosis produce?
Gametes
What are the stages of meiosis?
- The chromosomes are copied.
- The cell divides in two then immediately divide again.
- Four sex cells are produced with a single set of chromosomes.
Why is there variation from meiosis?
Each gamete has different genetic information. When the gametes fuse, variation is caused by the alleles.
Give an example of how stem cells can be used to treat illness.
Nerve cells can be injected into the spine to partially cure paralysis.
What are stem cells?
Unspecialised cells
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Give three issues with using stem cells.
- Embryonic stem cells come from aborted embryos.
- Embryonic stem cells might cause cancer.
- Making stem cells is difficult and expensive.
How did Mendel first discover inheritance?
He conducted breeding experiments with peas.
How could therapeutic cloning be used in healthcare?
A patient’s stem cells could be used to grow a genetically identical organ that could replaced a damaged organ.
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What are strands of DNA made of?
Four different chemical bases grouped in threes which each code for an amino acid.
What are DNA fingerprints?
Identifying unique patterns of DNA.
What does a gene do chemically?
Codes for a combination of amino acids.
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How is sex determined in humans?
The sex chromosomes determine.
XX is female
XY is male
What is a dominant allele?
An allele that controls development of a characteristic when there is only one.
What is a recessive allele?
An allele that only controls a characteristic if present in both chromosomes.
What is homozygous?
An individual with two identical alleles for a characteristic.
What is a genotype?
The genetic makeup of an individual regarding a particular characteristic.
What is heterozygous?
An individual with different alleles for a characteristic.
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Why is a phenotype?
The physical appearance of an individual regarding a particular characteristic.
What is polydactyly?
Extra fingers or toes
What is a genetic disorder?
Diseases that are the result of a problem in the genes that are passed on from parent to child.
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What causes polydactyly?
A dominant allele
What is cystic fibrosis?
An inherited condition when organs become clogged by thick mucus.
What are the chances of getting polydactyly?
- A parent with polydactyly and heterozygous gives 50% chance of the baby inheriting the disease.
- A parent with polydactyly and homozygous gives 100% chance.
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What is cystic fibrosis caused by?
A recessive allele.
What is a carrier?
A person not affected by the disease by has the allele for the condition.
What is the relationship of parent’s alleles with the child’s phenotype?
The inheritance is random.
What does a genetic diagram show?
- the alleles for a characteristic carried by the parents.
- the possible gametes that could be formed.
- how the genotype could affect the phenotype of the offspring.
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Give five arguments in favour of embryonic stem cells being used in medicine.
- Stem cells offer the best chance of finding treatment.
- The embryos would be thrown away anyway.
- Embryos are created from adult cells so wouldn’t become babies.
- It may be possible to use the umbilical cord so no embryos are destroyed.
- Stem cells could be used to grow new tissues.
Give four arguments against the use of embryonic stem cells in medicine.
- treatments are experimental so may cause further problems.
- all embryos have the potential to become babies.
- embryos cannot give permission to be used in experiments.
- money and research could be spent developing drugs.
What is mitosis?
Cell division into two identical daughter cells.
Give three advantages of genetic screening.
- people can decide whether or not to have any children.
- parents can decide whether to keep a baby with a disease.
- the parents can be sure the embryo is healthy before being implanted in the mother.
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