Genetic Info And Variation Between Organisms Flashcards
Define non coding base sequences and where are they positioned on genome
Base sequence that does not code for AA or protein.
Positioned between genes.
DO NOT MENTION INTRONS.
How many amino acids
20
Gametes have a … number of chromosomes
haploid
what does random fertilisation produce?
Different combinations of chromosomes from both parents.
Mixing of genetic material in sexual reproduction increases…
genetic diversity within species.
what process are gametes formed from?
meiosis
How many chromosomes do humans have?
46
what are chromatids
two copies of each chromosome
In meiosis, DNA condenses to form…
double-armed chromosomes, made from two sister chromatids
sister chromatids are joined by?
centromere
what are the products of meiosis
4 genetically different gametes - haploid number of chromo.
What leads to genetic variation?
-Crossing over
-Independent segregation
When does crossing over occur?
during meiosis 1
what is crossing over?
during meiosis 1 - homologous pair of chromosomes come together and pair up.
chromatids twist around each other, and bits of chromatids swap over.
chromatids contain the same genes but different combinations of alleles
What is independent segregation?
When chromosomes are separated in meiosis 1 its completely random - so daughter cells produced have different combinations
How is meiosis different from mitosis?
2 divisions
first separated homologous chromosomes, second then separated sister chromatids.
2 identical in mitosis
4 different in meiosis
What is the affect of chromosome mutation
causes errors in meiosis
What is non-disjunction?
failure of chromosomes to separate
What chromosome mutation causes Downs syndrome?
non-disjunction, homologous pair fails to separate.
3 copies of chromosome 21
How can a change in the base sequence in gene still result in a viable protein?
Degenerate nature of the genetic code.
Means multiple base triplets will code for the same amino acid.
So same tertiary structure of protein.
What are alleles?
Different versions of a single gene
What is genetic diversity?
The number of diferent alleles of genes in a species or population
How is genetic diversity in population increased?
Mutations in DNA - forming new alleles.
DIfferent alleles being introduced into a population when individuals from another population migrate - known as gene flow.
What is a genetic bottleneck?
catastrophic event that causes a massive reduction in the population.
What does the Founder Effect describe?
Describes what happens when just a few organisms from a population start a new colony and there are only a small number of alleles in the initial gene pool
What increases as a result of natural selection?
The proportion of advantageous alleles in the population
What is the taxa groups used to classify organisms?
Domain Kingdom Phylum Class Order Family Genus Species
Each group in the taxa groups is called a …
Taxon
What is species richness?
Measure of the number of different species in a community
What is biodiversity
the variety or living organisms in an area
Habitat
the place where an organism lives
Community
all the populations of different species in a habitat
Areas of high biodiversity will have …
lots of different species
Biodiversity can be measured using …
Index of diversity
When investigating biodiversity, the higher the number of d then the more …
the more diverse the area is.
