17. Inheritance Flashcards
what is inheritance
transmitting genetic information from one generation to the next
what is a chromosome
tightly packaged DNA around histone proteins in a thread-like structure that carries information in the form of genes
what is a gene
a section of DNA that codes for a specific 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 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 code for protein which can be enzymes, antibodies and receptors
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 protein 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 genes can be turned on or off dependent on the proteins the cell needs to make
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 may 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
- growth
- replacing worn out cells
- repairing tissues
- asexual reproduction
when does the duplication of chromosomes happen in relation to mitosis
the duplication of the chromosomes happens before mitosis
how is chromosome number maintained during mitosis
- the chromosome number doubles prior to mitosis
- during mitosis, each of the copies are separated, giving each daughter cell the original amount (23 pairs)
what are stem cells
cell that do not lose the ability to differentiate and so can differentiate into many different types of cells
what is meiosis
a type of nuclear division that produces four daughter cells that are not genetically identical
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 genes present for a trait
what is the phenotype
the visible characteristic
what is meant when an organism is homozygous
when an organism has two copies of the same allele
what is meant when an organism is heterozygous
when an organism has two different versions of the same gene
what is the term used to describe the type of breeding carried out when two homozygous individual 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
draw a Punnett square for a cross between a homozygous recessive blue eyed female (bb) with a heterozygous brown eyed male (Bb)
draw a Punnett square for a cross between homozygous dominant red flower (RR) with a homozygous recessive white flower (rr)
Draw a Punnett square for a cross between two heterozygous cystic fibrosis carriers (Ff)
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
Draw a Punnett square for a cross between a female with blood type A and a male with blood type AB
