B6.1 Reproduction Flashcards
Describe the cells produced by meiosis.
4 cells, genetically different.
Describe the cells produced by mitosis.
2 cells, genetically identical (clones).
What are gametes?
Sex cells.
Name the gametes in animals.
Sperm and egg.
Name the gametes in plants.
Pollen and egg.
Complete the sentence: “Sexual reproduction leads to …… in the offspring.”
Variety.
- State two differences between asexual and sexual reproduction (max 5).
“1. Asexual reproduction involves only one parent.
- No fusion of gametes.
- No mixing of genetic information.
- Genetically identical offspring.
- Only mitosis used.”
What effect does meiosis have on the number of chromosomes in a cell?
Halves it.
By what process is the number of chromosomes restored?
Fertilisation.
In animals, where are the gametes formed?
Ovaries and testes.
State the three key steps in meiosis.
“1. Copies of the DNA are made.
- The cell divides twice to form 4 gametes, each with a single set of chromosomes.
- All 4 cells are genetically different from each other.”
When a new cell is formed through fertilisation, how does it divide?
Mitosis.
What is the name of the process by which cells develop into specific cell types?
Fertilisation.
- State 3 advantages of sexual reproduction.
“1. Produces variation in the offspring.
- If the environment changes, variation gives a survival advantage by natural selection.
- Natural selection can be speeded up by humans in selective breeding to increase food production.”
- State 4 advantages of asexual reproduction.
“1. Only one parent needed
- More time and energy efficient as do not need to find a mate
- Faster than sexual reproduction
- Many identical offspring can be produced when conditions are favourable”
Describe how malarial parasites use both forms of reproduction.
Reproduce asexually in the human host, but sexually in the mosquito.
Describe how fungi use both forms of reproduction.
Reproduce asexually by spores but also reproduce sexually to give variation.
Describe how plants use both forms of reproduction.
Runners such as strawberry plants, or bulb division such as daffodils.
The genetic material in the nucleus of a cell is….
DNA
Describe the structure of DNA.
A polymer made up of two strands forming a double helix.
Name the structure within which DNA is contained.
Chromosomes.
What is a gene?
A small section of DNA on a chromosome.
What is the function of a gene?
To code for a particular sequence of amino acids in order to make a specific protein.
What is a genome?
The entire genetic material of an organism.
State 3 ways in which understanding of the human genome will be important.
“1. To search for genes linked to different types of disease
- To understand and treat inherited disorders
- To trace early human migration patterns”
Name the three parts of a DNA molecule.
A phosphate group, a sugar molecule and a nucleotide base
Name the four nucleotides found in DNA.
Adenine, thymine, guanine and cytosine
How many bases code for a particular amino acid?
3
What is a set of three nucleotide bases called?
A codon
Which cell organelle synthesises proteins?
Ribosomes.
How is the protein sequence correctly assembled?
Using a template molecule from the DNA.
What brings specific amino acids to the ribosomes?
Carrier molecules.
When the protein chain is complete, what process aids it to form its unique shape?
Folding.
Name three uses of proteins in the body.
“1. Enzymes
- Hormones
- Structural proteins e.g. collagen”
What is a change in the DNA sequence called?
A mutation.
Name three potential consequences for a protein of a mutation.
“1. No change or a slight change so no effect on the protein
- Altered protein, so an enzyme may stop working
- Mutation within a non-coding region nearby to a gene may affect the expression (production) of a protein”
What is a gamete?
A sex cell (egg or sperm; egg or pollen).
What is a chromosome?
A thread-like structure which contains coiled up DNA and proteins.
What is a gene?
A sequence of DNA nucleotide bases that codes for a specific protein.
What is an allele?
A different version of a gene.
What does the term “dominant” mean?
The individual only needs one copy of this allele for its phenotype to be seen.
What does the term “recessive” mean?
The individual needs two copies of this allele for its phenotype to be seen.
What does the term “homozygous” mean?
The individual has two identical alleles for this gene.
What does the term “heterozygous” mean?
The individual has two different alleles for this gene.
What is a genotype?
The genetic makeup of an organism for a particular gene (e.g. RR).
What is a phenotype?
The displayed characteristic due to the interactions between alleles (e.g. red flowers).
What is polydactyly?
A condition that causes the individual to have extra fingers or toes.
Is it a dominant or recessive condition?
Dominant.
State the genotype(s) that would result in polydactyly.
PP or Pp (homozygous dominant or heterozygous for this gene).
What is cystic fibrosis?
A condition which causes sticky mucus to build up in the lungs.
Is it a dominant or recessive condition?
Recessive.
State the genotype(s) that would result in cystic fibrosis.
cc (homozygous recessive).
How many pairs of chromosomes does an ordinary human body cell have?
23
How many pairs of chromosomes determine the sex of the individual?
1
What is the genotype of a female?
XX
What is the genotype of a male?
XY
