Genetics 1, 2, 3, 4 - Human genome, chromosomes and cell division, how genetics cause disease Flashcards
What 2 factors causes all disease?
Genetics and environment
In what direction is DNA always replicated and read?
5 to 3 direction
Bases in DNA?Bases in RNA?
DNA = ACGTRNA = ACGU
In DNA what bases pair?
Thymine and AdenineGuanine and Cytosine
In the nucleus, what is DNA wound around?
Proteins including histone proteins
What are genes?
Short sections of DNA - code for a specific protein by determining the order in which amino acids should be joined
What are chromosomes?
a thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
What are the 2 main phases of the ell cycle?
InterphaseMitotic phase
What happens during interphase?
The cell grows, accumulating nutrients needed for mitosis and duplicating DNA
What are the parts of interphase?
G1 - the cell makes new proteins for DNA synthesisG0 - the cell carries out its normal activitiesSynthesis - the cell replicates its DNAG2 - the cell prepares to divide
What happens during the mitotic phase?
The cell splits itself into 2 distinct cells (daughter cells)- genetically identical
What are the checkpoints in the cell cycle and what does each check?
G1 checkpoint = is the cell big enough and the environment suitable (if not, goes to G0)G2 checkpoint = has the DNA replicated, is the cell big enough, and the environment suitable?Mitosis checkpoint = are the chromosomes aligned on the spindle?
How many pairs of chromosomes does the normal human have?
23
What type of DNA damage can occur during replication? (3)What conditions mean that you cannot repair these damages?
DNA strand breaks (BRCA1/2)Chemical cross linking (Xeroderma pigmentosa)Mismatched base (hereditary colorectal cancer)
What happens during mitosis?
1 diploid parent cell becomes 2 identical diploid daughter cells
What happens during Meiosis?
a diploid cell, ordinarily having two complete sets of chromosomes, gives rise to 4 haploid cells (gametes) each having one set of genetically different chromosomes (germ cell forms either 4 sperm or 4 egg cells)
What are the stages in meiosis?
DNA replicates and recombines (crossing over occurs)Cell division 1Cell division 2
How are the chromosomes produced during meiosis genetically unique?
Due to crossing over
How is RNA different to DNA?
Single strandedRibose is backbone instead of deoxyriboseUracil is used instead of thymine
What parts of DNA are spliced out after transcription?
Introns
What is the amount of protein produced determined by? (4)
Rate of transcription (manufacture of pre-mRNA)Rate of splicing to mRNAHalf life of mRNARate of processing of polypeptide
What converts DNA to pre-mRNA?
Transcription
What converted pre-mRNA to mRNA?
Splicing
What converts mRNA to protein?
Translation
What do 3 bases encode?
1 amino acid or a stop
What is a polymorphism?
The occurrence of a chromosome or a genetic character in more than one form, resulting in existence of more than one morphological type in the same population (population frequency of greater than 1%) - variation in the human genome that does not cause a disease it its own right but may however predispose to a common disease
What is a single nucleotide polymorphism?
a DNA sequence variation occurring when a single nucleotide - A, T, C, or G - in the genome (or other shared sequence) differs between members of a species (or between paired chromosomes in an individual)
What is a mutation?
Disease causing genetic change
What does a mutation in FGFR3 cause?
Achondroplasia
What are the 4 stages of mitosis?
ProphaseMetaphaseAnaphaseTelophase
What is a chromatid?
One of the 2 copies of the DNA that are joined at the centromere and make up the chromosome during cell division
What happens during prophase?
The chromosomes appear condensed and the nuclear membrane disappears
What happens during metaphase?
The chromosomes line up along the metaphase plate
What happens during anaphase?
The chromatids of each chromosome are separated and pulled apart to opposite ends of the cell
What happens during telophase?
The chromosomes are at either poles of the cell and the nuclear membrane reappearsThe cytoplasm starts to divide
What is a karyotype?
The number and appearance of chromosomes in the nucleus of a eukaryote cell (picture of the chromosomes)
What are the darker areas in a karyotype?
The areas of DNA that have less genes
How many autosomes does a human have?
22 pairs = 44
Parts of a chromosome?
TelomereShort arm (p)CentromereLong arm (q)Telomere
How many divisions can the average cell make?
60 - 100
What is phenotype?
the observable characteristics of a person which result from his genotype and the environement
What is an acrocentric chromosome?
A chromosome in which the centromere is located quite near one end of the chromosome. Humans normally have five pairs of acrocentric chromosomes
Parts of an acrocentric chromosome?
Satellite ribosomal genes, tRNAs, etc.CentromereLong arm
What is satellite DNA?
very large arrays of tandemly repeating, non-coding DNA