B5.1-Inheritance Flashcards
What is a recessive allele?
An allele that is only expressed if you have two copies of the allele, one from each parent
What are the advantages and disadvantages of asexual reproduction ?
Advantages: if an offspring is well adapted to the area it will share an identical set of characteristics It is faster since only one parent is needed Disadvantages: changes to biotic and abiotic factors may result in the whole species dying out
Are all mutations harmful?
Not all mutations are harmful some mutations are neutral (neither benefit nor harm the organisms) Some can even be beneficial as conjugation in bacteria allows for antibiotics in plasmids to be transferred between cells
What is the second stage of meiosis?
- The chromosomes line up along the middle of each of the new cell 7. This time each chromosome is pulled in half. A single copy of each pair is pulled to opposite ends of the cell 8. The cell then divides into two. This results in four haploid cells that are genertically different
What is asexual reproduction?
Asexual reproduction is when an organism reproduces itself without a mate. This produces a clone with the exact genetic makeup of the parent
What is a gamete?
A gamete is a sex cell produced during sexual intercourse. It is a haploid cell since two gametes fuse to form a zygote (diploid cell).Examples are sperm and egg cells
How many pairs of chromosomes does a human have?
A human has 23 pairs of chromosomes. 22 pairs are identical in appearance. The 23rd pair known as the sex chromosomes are different. Two X chromosomes makes a girl and an X and a Y chromosome makes a boy.
What is sexual reproduction?
Sexual reproduction requires two parents. The offspring is not a clone since it is made from two sets of genes. This causes variation
What is the genotype?
Genotype is the genetic make up of an organism
What is the phenotype?
Phenotype is the physical characteristics of an organism e.g. hair colour, eye colour and skin colour
How can someone be heterozygous?
If someone has two different alleles
What do mutations affect?
Mutation affects an organisms genotype and rarely affects phenotype
How can a mutation affect phenotype?
If a mutation occurs within a gene dna bases may be changed or deleted. This changes the reading of the triplets so coding for different amino acids which code for different proteins and so affecting the phenotype
What is a haploid cell?
Cells that have 23 chromosomes (or D). They are produced in meosis.
What causes variation?
A group of genes controlling a certain variation
What are some examples of dominant characteristics?
Dark wavy hair, brown eyes, free ear lobes, freckles and a straight nose
What is a dominant allele?
A dominant allele is an allele that expresses itself even if you get it from one or both parents
What are examples of plants that can reproduce asexually?
Potato plants, spider plants and daffodils
How can you predict the outcome of a genetic cross?
By stating the phenotype ant genotype if the parents and making a punnet square diagram
Why is there a roughly the same amount of boys and girls in a population?
Because there is a 50% chance of conceiving a boy and a 50% chance of conceiving a girl
What are examples of recessive characteristics?
Straight blonde hair, blue eyes, no freckles, joined ear lobes and upturned nose
What is a genetic variant?
A genetic variant is a different version of an allele, which is caused by a change in the DNA. All variants occur from mutation
What is environmental variation?
Variation caused by the environment you live in
Are most mutations harmful?
Most mutations are harmful; They can cause cancer (cells divide uncontrollably) They can cause the production of abnormal protein channels (channels that allow molecules to be transported through the cell membrane) that do not function properly e.g cystic fibrosis
What is a genome?
A genome is the entire genetic material of an organism. All individuals produced by sexual reproduction have different genomes except for identical twins
What are the advantages and disadvantages of sexual reproduction?
Advantage: variation in offspring will happen and will adapt to environmental pressure. This will kill out the species with unfavourable characteristics and so the organisms with favourable characteristics will reproduce and the species will continue Disadvantage: it takes to parents. Reproduction is slower so less offspring are produced
What is genetic variation?
Genetic variation is the genetic material you inherit from your parents
How can someone be homozygous?
If you have two copies of the same allele
What is variation?
Variation is the differences within a species
What is an allele?
Different forms of a gene
How does genetic variation occur?
You have two copies of a gene for each characteristic -one from each parent. So you are different to both your parents
What is a mutation?
A mutation occurs when a sequence of DNA bases is altered. They can occur spontaneously
What is a diploid cell?
A diploid cell has 46 chromosomes (or 2D). They are produced by mitosis
What is meiosis?
Meiosis is the process whereby one parent haploid cell creates 4 daughter cells. It happens in the ovum and the testes
What is the first stage of meiosis?
- The chromosomes are copied 2. These chromosomes line up along the equator of the cell (one from each parent) 3. One member of each pair is pulled to opposite ends of the cell 4. The cell divided in two 5. Two separate cells are formed
How do most phenotypes arise?
When a group of genes code for a specific characteristic e.g eye colour
How do mutations affect non coding dna?
Non coding dna such as mRNA affect how a gene is expressed. Therefore mRNA may not be able to be replicated and is not produced at all.
