15. Evidence for evolution + 16. fossil evidence for evolution Flashcards
What are the types of comparative studies in biochemistry?
Mitochondrial DNA
Protein Sequences
DNA
What does it mean if species share a greater portion of their DNA?
they are more closely related
What are endogenous retroviruses?
a viral sequence that has become a part of an organisms genome
retrovirus RNA enters cell and is copied into DNA –> reverse transcription –> DNA then inserted into host cell chromosome
only endogenous if it inserts into gamete cell (all subsequent generations have a copy of the virus in their cell
comprise about 8% human genome
What is mitochondria?
cell organelles where aerobic respiration occurs to release energy for cell use
What is mtDNA?
DNA in the form of small circuar molecules (5-10 in each mitochondrian)
- 37 genes
- 24 contain code for making tRNA
13 code for cell respirations reactions
rare diseases caused by mutations in mtDNA
higher rate of mutation –> slowly diverges from ancestral copies, amount of mutation is proportional to the amount of time that has passed
What is easier to extract, mtDNA or nuclear DNA and why?
mtDNA due to the fact that most cells contain large numbers of mitochondria
Why does mtDNA only come from the mother?
sperm destroys the mitochondria after entering a cell
what does it mean if the mtDNA is very similar?
two individuals are closely related, but if not similar their last common maternal ancestor lived a long time ago
What is DNA?
Deoxyribonucleic acid- very large molecule made of two strands of nucleotides that are joined by bonds between the nucleotide bases. The two strands are twisted into a double helix
found in the nucleus and mitochondria of cells
what is nDNA?
Nuclear DNA- DNA found in the nucleus of the cells
what is mtDNA?
mitochondrial DNA- DNA found in the mitochondria
What is RNA?
Ribonucleic acid - large molecule composed of a single strand of nucleotides
what is mRNA?
RNA molecule that carries the code for protein synthesis from the DNA in the nucleus to the ribosomes where the protein is made
what is tRNA?
Transfer RNA- a small RNA molecule that transfers the correct amino acid to the ribosome for inclusion in the protein molecule being made
what are ubiquitous proteins?
in all species, perform basic and essential tasks, independent of organism’s specific function or environment
what is Cytochrome C?
- performs essential step in production of cellular energy
- changes very little over evolution
- 37 amino acids in the same place in every sequenced molecule –> proteins have descended from an ancestral molecule found in primitive microbe more than 2000 million years ago
- sequences from different species are aligned and compared
what is annotation?
identification of genes and other biological features in a DNA sequence
- a computerised process, made possible by the fact that genes have recognisable start and stop codons
what are comparative studies in anatomy?
embryology
homologous organs
vestigial organs
what does embryology do?
provides evidence for evolutionary change over time by comparing the early stages in the development of organisms
how is embryology done?
by comparing embryos of different species during a pregnancy
the longer the species is similar in development, the more closely related they are
how can you tell vertebrae are related through embryology?
many vertebrae have embryonic gill pouches and arches, as well as absence of paired appendages and all have a tail (embryonic reptiles, birds and mammals) which show their common ancestor in fish millions of years ago
what are homologous organs?
possess a similar internal structure but different external appearance or function
They are likely to have a common ancestor
what are vestigial organs?
structures of a reduced size that appear to have no function, but long ago in the evolutionary timeline had a function that has diminished due to changed environment
what are examples of vestigial organs?
- nicitating membrane present in corner of each eye
- external ear muscles
- wisdom teeth erupt abnormally
- appendix
- coccyx
- erectopilli muscles
how can geographical distribution be used to provide evidence for evolution?
- the more similar structures are whilst being found in very different places shows a common ancestor
what are fossils?
any preserved trace by an organism from a previous time period, including footprints, burrows, teeth, faeces, bones, impressions of organisms, or footprints