Topic 17 Flashcards
What is inheritance?
Transmitting genetic information from one generation to the next
What is a chromosome?
Long lengths of DNA + carries information in the form of genes
What is a gene?
A section of DNA that codes for a specifc protein
What is an allele?
Different versions of the same gene
How is sex determined by genes?
“One of the 23 pairs of chromosomes determines sex
The pair can either be XX for a female or XY for a male”
Describe how genes determine the order of amino acids in a protein
The sequence of bases in a gene relates directly to the amino acids added during protein synthesis
How does DNA control cell function?
DNA codes for proteins which can be enzymes, antibodies and receptors (for example)
Explain protein synthesis
“A copy of the gene is made using mRNA and taken into the cytoplasm to a ribosome
The ribosome assembles amino acids into proteins based on the sequence of bases in the mRNA molecule”
Compare the genes found in all the body cells
“All body cells contain the same genes
However not all cells express all, only needed ones for their function
What is a haploid nucleus
A nucleus with one set of unpaired chromosomes
What is a diploid nucleus
A nucleus with two sets of chromosomes where there is a pair of each type of chromosome
How many pairs of chromosomes does a human diploid cell have
23 pairs
What is mitosis?
A type of nuclear division that produces two genetically identical daughter cells
State 4 uses of mitosis
Cell growth
Repair of cells
Replacements of cells
Asexual reproduction
When does the duplication of chromosomes happen in relation to mitosis?
“The duplication of the chromosomes happens before mitosis
“
What are stem cells?
Cells that can differentiate into many different types of cells
What is meiosis?
A type of reduction division which halves the chromosome number, producing four genetically different daughter cells
What type of cell does meiosis produce?
Sex cells (gametes)
How does meiosis produce genetically different daughter cells?
Meiosis combines maternal and paternal chromosomes in different ways
What is the genotype?
The alleles present
What is the phenotype?
The visible characteristic
What is meant when an organism is homozygous?
Having 2 identical alleles for a particular gene
What is meant when an organism is heterozygous?
When an organism has two different versions of the same gene (one dominant and one recessive)
What is the term used to describe the type of breeding carried out when two homozygous individuals breed?
Pure-breeding
What is a dominant allele?
A version of a gene where only one copy is needed for it to be expressed
What is a recessive allele?
A version of a gene where two copies are needed for it to be expressed
What do family pedigrees show?
The inheritance of an allele over generations
What is a test cross?
“A method used to identify an unknown genotype
It is done by breeding the unknown organism with a homozygous recessive organism”
What is codominance?
When two alleles affect the phenotype
What is a sex-linked characteristic?
“A characteristic where the gene responsible for its located on a sex chromosome
This makes it more common in one sex than another”
Give one example of a sex-linked characteristic?
Colour blindness
