Unit 4 Topic 1 Bio Flashcards
What is DNA made out of?
Nucleotides.
What makes up a Nucleotides?
- A phosphate group.
- A sugar group.
- A nitrogen-containing base.
What are DNA strands? And how does it work?
- When nucleotides join to form a polynucleotide chain, or strand.
- The sugar and phosphate groups join by covalent bonding to form the backbone of the DNA molecule.
What are the 5 different nitrogen bases?
- Adenine (A).
- Guanine (G).
- Cytosine (C).
- Thymine (T).
- Uracil (U).
How is DNA packaged?
When DNA condenses during cell division, DNA is packaged tightly into chromosomes which are found in the nucleus. This is done by wrapping around histone proteins which continually wrap and coil to create a supercoil.
Where is DNA found in Prokaryotic and Eukaryotic cells.
Prokaryotes: DNA is found in the cytoplasm of prokaryotes as unbound circular DNA.
Eukaryotes: Most of the DNA is in the nucleus in chromosomes. Some DNA is also found in the mitochondria and chloroplast as unbound circular DNA.
What are Sister Chromatids?
When DNA is replicated, one chromatid is copied to create two chromatids. These contain the same DNA.
What are Homologous Chromosomes?
Two different chromosomes from each parent that encode the same information.
Identify the first stage of Meiosis 1 and define it.
Prophase 1 -> Homologous chromosomes condense and come together to form a tetrad. Crossing over and recombination occurs where multiple segments of non-sister chromatids overlap, break and reattach to the other chromatid, creating variation.
What is Helicase?
An enzyme that unzips the two strands to create a replication fork
What is DNA polymerase?
An enzyme that adds nucleotides to the template strands to build two complementary strands.
Recall the stages of mitosis.
Interphase, Prophase, Metaphase, Anaphase, Telophase.
Describe the phases of Meiosis.
Meiosis:
Define Spermatogenesis.
The production of sperm in the testes.
Approx 400 million sperm daily.
Define Oogenesis.
When only one viable haploid cell over a series of events is produced through Meiosis.
Define Independent Assortment.
Recombined chromosomes are aligned at the equator.
Define Random Fertilisation.
If two people reproduce, the random chance of any one sperm and egg coming together is estimated to have some 70 trillion possible combinations.
Define a Gene
A sequence of nucleotides that encodes the synthesis of a gene product, either RNA or protein.
Define a Genome
The complete set of genetic material (DNA) present in an organism, measured in the number of base pairs contained.
What is contained within a genes structure
Start Codons
Stop Codons
Promoter Regions
Coding Regions -> Exons
Non-Coding Regions -> Introns
Define the purpose of Exons
Exons are used to make proteins or RNA
Define Transcription
The synthesis of mRNA from DNA.
Identify the steps of Transcription
Initiation, Elongation, Termination.
Define Initiation
RNA polymerase binds to the promoter region of the gene and breaks the hydrogen bonds between strands, causing them to separate and create a ‘transcription bubble’.
Define Elongation
The RNA polymerase moves along the gene, nucleotides are added by complementary base pairing. The DNA strands behind the transcription bubble recoil back together as the mRNA is forming.
Define Termination
Transcription ends when RNA polymerase reaches the termination site of the gene. This region contains a stop codon which causes RNA polymerase to detach, releasing mRNA.
Define Translation
The information in mRNA is read and used to build a chain of amino acid.
Identify the key component of translation. And define.
Ribosomes. They contain two subunits that come together around the mRNA strand. Then tRNA is used to add the specific amino acid to the chain.
Define Gene Expression
Produces a functional gene product, either protein or functional RNA.
Define Transcription Factors
Proteins that bind to specific sequences to control gene expression.
Identify the causes of mutation
DNA replication, Cell division, Damages by mutagens.
Identify the 2 mutations that can lead to errors in DNA replication.
Point Mutation, Frameshift mutation.
Define a Point Mutation
Involves a change in one base in the sequence.
Define a Frameshift mutation
An insertion or deletion of one or more bases, shifting several codons.
Define Autosomal Dominant
A trait that is often seen in all generations.Must have one parent with the trait.
Define Autosomal Recessive
Neither parent has a phenotype but one or more offspring do.
Define X-Linked Dominant
Males who are affected will always have daughters with the trait and sons without (rare).
Define X-Linked Recessive
Females who are affected will have sons with the trait.
Define Y-Linked Inheritance
Only males can be affected and pass down to all sons.
What is a Polymerase Chain Reaction or PCR?
A single or few copies of DNA are replicated into millions or billions of copies.
