What is a test cross?
rossing a homozygous recessive individual with one expressing the dominant trait to determine whether or not the dominant trait is heterozygous or homozygous.
What are alleles?
Characteristics or features of an organism
What is a genome?
The complete complement of an organisms or viruses genetic material
What is a gene?
A segment of DNA molecule codes a specific trait
What is a locus?
The location of a gene in a chromosome
What is chromatin?
A mass of thread like strands of DNA
What are chromosomes?
Cellular structures of very long DNA, sister chromatids are joined copies of a chromosomes
What are the 3 steps of the cell cycle?
Interphase, Mitosis, cytokinisis
What happens in interphase?
DNA makes a copy, G1 and G2, the in between stages of dviding
Gnot phase?
Resting phase, nothing happens
What is necrosis?
Cells die due to external factors
What is apoptosis?
Programmed and targeted cells
What is a diploid?
Contains 2 complete sets of chromosomes (somatic cells)
What is a haploid?
Contains a single set of unpaired chromosomes (sex cells)
What happens in prophase?
Chromatin condense into chromosomes, nuclear membrane dissolves, spindle fibres form, nucleolus dispersal
What happens in metaphase?
Chromosomes line up in the middle of the cell, with the help of spindle fibers
What happens in anaphase?
Chromosomes separate into 2 identical sets as sister chromatin are pulled to opposite poles of the cell
What is telophase?
Chromosomes reach the poles and unwind, and nuclear membrane forms
What happens in meiosis?
Hereditary material is exchanged
what happens in prophase 1?
Chromatin condenses into chromosomes, homologous chromosomes pair up to make tetrods, crossing over happens in late prophase 1
What is crossing over?
Homologous chromosomes exchange portions of DNA resulting in offspring that are genetically diffrent
What happens in metaphase 1?
Chromosomes line u p across middle, the random assortment of chromosomes happen here
What happens in anaphase 1?
the chromosomes separate independently
What happens in meosis telophase and interphase?
cell begins to divide and can get any combination of chromosomes
How many daughter cells does meosis make?
4
what is aneuploidy?
Having an abnormal amount of chromosomes
What is nondisjunction?
failure of homologous chromosomes to separate in anaphase
What is monosomy?
karyotype missing one chromosome
what is trisomy?
Condition where there are more chromosomes than required
What is a kayrotype?
organised picture of a persons chromosomes
What is klinefelter syndrome?
Male with an extra copy of the x chromosome
What is turner syndrome?
Missing or damaged x chromosome
What does DNA stand for?
Deoxyribonucleic Acid
What did Friendrich miescher do?
Started investigating a compound found in the nucleus of the cell (1869)
What did rosaland frankllin do?
Took an x-ray photo of DNA (1952)
What did watson and crick do?
discribed the features of DNA in franklins picture (1953)
What does DNA consist of?
a dexoyribose sugar, a phosphate and a nitrogen containing a base
What are the purines?
Adenine and Guanine
What are the pyrimidines?
Thymine and cytosine
What are the 3 types of DNA mutation?
Subsatution, Insertion, Deletion
What is dominant inheritance?
Only one copy of the gene needs to have the mutation for it to be expressed
What is recessive inheritance?
2 copies of the mutation in the gene must be present to be expressed
What are sister chromatids?
Joined copies of the orgnial chromosome
What is G1 for?
Growth and preperation
What is the S phase for?
DNA replecation
What is the G2 phase for?
Preparation for mitosis
what happens in cytokinisis?
Cells seperate fully
What is interkenisis?
It is a period of rest between meiosis 1 and meiosis 2
What is Polyploidy?
Nondisjusction of all the the chromosomes
What is DNA wrapped around?
Hitones (protiens)
What kind of backbone does DNA have?
Phosphate sugar
What is the key to diveristy in DNA?
Different arrangements of nuclitoids
What happens when DNA mutates?
It might have no effect, the amino acid may be similar to the one it replaces or it can be deadly
What happens in substitution?
A new base completely replaces the old base
What happens in insertion?
A whole new compound is added, pushing all the bases forward
What happens during deletion?
A base pair is completely taken out, moving the other bases backward
What is genetic screening?
any procedure used to identify individuals with an increased risk of passing on an inherited disorder.
What is genetic counselling?
The giving of advice to prospective parents concerning the chances of genetic disorders in a future child.
What is a pedigree?
the recorded ancestry, especially upper-class ancestry, of a person or family.
What is prenatal diagnosis?
The purpose of prenatal diagnosis is to test the fetus for a genetic problem for which the family is at risk.
What is Amniocentesis?
14-16 weeks into pregnancy.
a needle is pushed through the abdominal wall.
amniotic fluid is withdrawn and centrifuged.
fetal cells in the fluid are isolated and a karyotype is made.
What is chorionic villus?
9 – 12 weeks into pregnancy
tube inserted intravaginally
cells from chorionic membrane are suctioned out
fetal cells are isolated and a karyotype is made
What is Recombinant DNA?
The purpose is to produce missing proteins to allow us to treat people with defective genes.
What is gene therapy?
Inserting a working copy of a gene into the cells that lack the ability to produce their own protein.
What is . The Human Genome Project?
The Human Genome Project was an international scientific research project with the goal of determining the base pairs that make up human DNA, and of identifying, mapping and sequencing all of the genes of the human genome from both a physical and a functional standpoint.
What is cloning?
Cloning involves make exact copies of an original organism.The clone will be genetically identical, but not necessarily phenotypically identical to the parent.
What is the law of segregation?
Each gamete receives one copy of each chromosome, and therefore one copy of each gene, so one allele for each gene.
What are the autosomal ressive disorders?
Sickle Cell Disease, Tay-Sachs Disease, Cystic Fibrosis:
What is an autosomal dominant disorder?
Huntigtons disease
What are the x linked traits?
Hemophilia
Muscular dystrophy
Red/green colourblindness
Early patterned baldness