compendium 12\ Flashcards
structure of proteins
long chains of amino acids linked together by peptide bonds
functions of proteins
Regulation -
Transport -
Protection -
Contraction -
Structure -
Energy -
structure of proteins
Primary - sequence of amino acids linked by peptide bonds
Secondary - folding of proteins, two main types = alpha helices and beta sheets. Results from hydrogen bonds
Tertiary - the 3d shape determined by the folding
Quaternary - combined 3D structure of 2 or more polypeptide chains
Eg haemoglobin consists of 2 alpha and 2 beta chains
Two types of proteins
fibrous
globular
fibrous proteins
single, elongated polypeptide chains
Insoluble in water and stable
Provide support and strength
Less sensitive to changes in temp and pH
globular proteins
polypeptide chains folded into compact shape
Water soluble
Mobile, chemically active
Sensitive to changes in temp and pH
structure of nucleic acids
large molecules composed of carbon, hydrogen, oxygen, nitrogen and phosphorus
DNA
2 strands, double helix
deoxyribose
ATCG
very long
RNA
1 strand
ribose
AUCG
shorter
components of a nucleotide
pentose sugar - deoxyribose or ribose
Phosphate group
Nitrogenous base - adenine, guanine, cytosine, thymine, uracil
Genetic code
specific arrangement of nucleotides
transcription
occurs in nucleus
DNA to mRNA
DNA has 2 strands, coding strand and template strand
Two strands unzip
RNA polymerase binds to the promoter region
Genetic info is copied from the template strand of DNA to make a strand of mRNA
Transcription ends at the terminator sequence
mRNA exists nucleus through nuclear pores into the cytoplasm
translation
occurs in cytoplasm
mRNA to protein
Carries genetic info from nucleus to ribosomes
Translation starts at the start codon (AUG)
Each codon codes for a specific amino acid
As each codon is read tRNA with a complimentary anticodon binds to each triplet
The tRNA carries the amino acid specific for that codon
Amino acids are joined together by peptide bonds
post translational modification
chemical modification of a protein following translation
Modified by attaching functional groups which can change or extend its function
role of mRNA
takes the information from the genes (DNA) in the nucleus out to the ribosomes
role of tRNA
transfers amino acids from the cytoplasm to the ribosome and lines them up opposite their mRNA codon
role of r RNA
major structural component of the ribosome
role of r RNA
major structural component of the ribosome
cell cycle
spends majority of its time in interphase
Interphase: phase between cell divisions, has 3 stages
G1 - routine metabolism
Synthesis phase - DNA replication
G2 - prepare for division
Mitosis: series of events that leads to production of 2 somatic cells by division, cells are genetically identical
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis - division of cell cytoplasm
mitosis
IPMAT
Interphase - cell undergoes normal growth and metabolic process and prepares to divide
3 parts
G1 - normal metabolic activities
S - DNA replicates producing 2 identical copies of each chromosome
G2 - cell prepares for division, organelles replicate
Prophase - chromatin condenses into chromosomes, centrioles move to opposite ends of the cell, spindle fibres form and move towards equator, nuclear envelope forms
- chromatin condenses so that the DNA is protected during cell division and easier to divide in half
Metaphase - chromosomes align in the middle of the cell, spindle fibres attach to centromeres of the chromosomes
Anaphase - chromatids separate and move towards centriole, cleavage forms
Telophase - migration of chromosomes is complete, nuclear envelopes reform, continue to split into two cells
Cytokinesis - division of organelles and cytoplasm, results in 2 daughter cells
Describe how mitosis differs from meiosis.
In meiosis they can undergo crossing over
During the second stage the cell divides and pulls one of each pair of homologous chromosomes into the daughter creating haploid number
meiosis
germ cells divide producing gametes
1 replication, 2 divisions
Early prophase 1
chromatin condenses into chromosomes, centrioles move to opposite ends of the cell, spindle fibres form and move towards equator
2. Middle prophase 1
homologous crossing over = DNA is exchanged between adjacent chromatids results in new gene combination and human variation
3. Metaphase 1
chromosomes align in the middle of the cell, spindle fibres attach to centromeres of the chromosomes, random assortment of chromosomes
4. Anaphase 1
chromosomes separate and move towards centriole, cleavage forms
Chromosomes dont split like mitosis
5. Telophase 1
migration of chromosomes is complete, nuclear envelopes form, continue to split into two cells
Two non identical cells
No replication before meiosis 2
6. Prophase 2
each chromosome has 2 chromatids
7. Metaphase 2
chromosomes align in the middle of the cell, spindle fibres attach to centromeres of the chromosomes
8. Anaphase 2
chromatids separate and move towards centriole, cleavage forms
9. Telophase 2
migration of chromosomes is complete, nuclear envelopes form, continue to split into 4 cells each with 23 chromosomes (haploid)
amino acids
20 amino acids
- Each amino acid has an amine group, carboxyl group, hydrogen atom and a side chain (R)
Dipeptide
2 amino acids
Oligopeptide
3-10 amino acids
Polypeptide
10 or more amino acids
Protein
50 or more amino acids
Peptide
short chain of amino acids 2 or more amino acids
Histone
dna wrapped around proteins
Chromatin
histones and DNA bundled together
Chromosomes
chromatin twists and condensed together
Karyotype
map of chromosomes in a dividing cell
Somatic cells
23 pairs of chromosomes diploid
Gamete cells
23 chromosomes haploid
Germ cells
give rise to gametes, located in gonads
Autosomal chromosomes
humans have 22 pairs
Sex chromosomes
humans have 1 pair, either XY (male) or XX (female)
Genetics
study of heredity
Gene expression
production of proteins from the information stored in DNA, involves two steps transcription and translation
Gene
segment of dna that codes for a protein
Allele
alternative form of a gene
Genotype
the actual gene eg AA, Aa, aa
Phenotype
physical characteristic eg colour of hair or eyes
Proteome
all proteins that the cell makes
Proteomics
study of proteins in a cell
Sex linked traits
traits affected by genes on the sex chromosomes
Homologous chromosomes
pairs of chromosomes where one is from the father and one from mother
Locus
location of a gene on a chromosome
Zygote
egg and sperm join to form a zygote
Diploid
full amount of DNA, eg all cells in the body except for gametes
Haploid
half the amount of DNA eg gametes (egg and sperm)
