Chapter 16 - Chromosomes, genes, and proteins Flashcards
What is the function of DNA?
DNA stores genetic information and codes for proteins
What is a chromosome?
Chromosome is made of DNA which contains genetic information in the form of genes
What is a gene?
A length of DNA that codes for a protein
What is an allele
An alternate form of a gene
Why do homologous chromosomes pair up?
Because they are a similar size
What is DNA replication?
The sequence of bases on the DNA is copied to produce two identical DNA molecules
What is mitosis?
Mitosis is nuclear division giving rise to genetically identical cells
What is mitosis used for?
Growth
Repairing damaged tissue
Replacing worn-out cells
Producing new organisms by asexual reproduction
What is meiosis?
Nuclear division giving rise to genetically different cells
What is meiosis used for?
Production of gametes
How does meiosis produce variation?
Crossing over
Independent assortment
Random Fusion of gametes at fertilisation
What is meant by genotype?
The genetic make-up of an organism in terms of the alleles present
What is meant by phenotype?
The observable features of an organism
What is meant by homozygous?
Having 2 identical alleles of a particular gene
What is meant by dominant allele?
An allele that is expressed if it is present
What is meant by recessive allele?
An allele that is only expressed when there is no dominant allele of the gene present
What is Monohybrid Inheritance?
The inheritance of a single characteristic that is controlled by one gene
What is Codominance?
When the alleles are both expressed in the phenotype when they are both present . The heterozygous offspring shows a third phenotype ( an intermediate ) that is different from the two homozygous phenotypes e.g. Red and White, heterozygous offspring are pink
What is a test cross?
A test to identify the unknown genotype of an organism showing a dominant phenotype. One of the parents must be homozygous recessive
Which chromosomes can be provided by the females and males respectively?
Females can provide the X chromosome only
Males can provide X or Y chromosome
The gender of the baby is determined by the father
What is a sex-linked characteristic?
A characteristic controlled by a gene on a sex-chromosome, and occurs more commonly in one sex than the other.
More males are affected that females, and only females are carriers
What are sex-linked genes?
Genes that are found on the X chromosome, and only one allele will be present in males
How does DNA control cell function?
DNA controls cell function by controlling the production of proteins, such as enzymes, antibodies and receptors for neurotransmitters
How does the sequence of bases in genes determine the final shape and function of the protein?
The sequence of bases in genes determines the sequence of amino acids. The specific sequence of amino acids determines the final shape and function of the protein
