inheritance Flashcards
gene
a length of DNA that codes for a protein
alleles
alternative versions of a gene. A section of DNA that codes for a particular protein
chromosomes
thread-like structures in which DNA is coiled and packed
what do genes and alleles provide?
variation in populations
What structure does DNA have?
Double helix structure
genetic code
the sequence of bases in a gene
What does the genetic code determine?
The order in which amino acids are joined together to make a specific protein
Where does protein synthesis occur?
In the ribosomes
messengerRNA (mRNA)
a type of genetic material that carries genetic information from the nucleus to ribosomes to make protein
stages in protein synthesis (4)
- A DNA molecule in the nucleus unzips, exposing the bases in a gene.
- An mRNA molecule is formed using the exposed bases of the DNA strand as a template. The bases in the mRNA molecule pair with the complementary bases in the DNA, so the mRNA molecule carries a copy of the gene.
- The mRNA molecule moves out of the nucleus into the cytoplasm.
- A ribosome reads the mRNA code and joins amino acids together to form a protein, following the specific sequence of bases in the mRNA
mitosis
type of nuclear division that gives rise to genetically identical cells
What is mitosis responsible for and involved in?
responsible for the repair of damaged tissues and the replacement of cells involved in asexual reproduction
What must occur before mitosis?
DNA duplication so that there is enough DNA for each new cell
Mitosis produces
diploid cells
Meiosis
type of nuclear division that gives rise to genetically different cells
Meiosis produces
haploid cells
what is meiosis involved in?
involved in the production of gametes
Meiosis is involved in what type of reproduction?
Sexual reproduction
In meiosis, the number of chromosomes is…
halved
In meiosis a diploid cell becomes
four haploid cells
homozygous
two identical alleles
heterozygous
two different alleles
phenotype
observable features of an organism
genotype
all the alleles present in that organism
pure-breeding
two identical homozygous individuals breed together
dominant allele
always expressed if it is present
recessive allele
only expressed if the dominant allele is not present
test cross
a cross with a homozygous recessive individual, used to determine the genotype of an individual showing the dominant trait
involves breeding an individual with a phenotype from a recessive allele with the individual with the unknown genotype
co-dominance
when two different alleles for a characteristic influence the phenotype to the same extent
