Chapter 5 Flashcards
what are chains of amino acids?
proteins
DNA consists of ?
two phosphate backbones joined by a series of bases
Which base belongs to with complimentary base: A,T,C,G
A - T
C - G
Concept to remember
When a cell divides, the strands of DNA are separated and new complementary strands are added. As a result, the two new DNA strands are identical to the original one
how do cells expose or hide genes?
by winding and unwinding DNA around histones
what is the number of copies of unique chromosomes in a cell?
Ploidy
_______ is the number of different chromosomes in a gamete cell (n)
In _______ organisms, this number is doubled in somatic cells (2n) because _________
Triploid and tetraploid organisms have 3n and 4n chromosome copies in their somatic cells, respectively, and many plants have even higher ploidy numbers.
- Haploidy (n)
- Diploid (2n) because there are two copies of each of the unique chromosomes
how many chromosomes do humans have?
22
females have paired _ chromosomes, and males have a ___ _ chromosome and a ___ _ chromosome.
females have paired x chromosomes, and males have a single X chromosome and a single** Y** chromosome.
Ribosomes translate ____ into ____.
mRNA into protein
Concepts to remember
Each messenger RNA molecule acts as a template for building a protein. The ribosome reads three bases at a time (a codon), and a transfer RNA “hooks on” the correct amino acid.
Edit
Bacteria have small regulatory sequences near protein-coding regions where proteins can bind, promoting or repressing the expression of those genes. Eukaryotic genes have much more complex mechanisms for gene regulation: their activators, transcription factors, and other molecules cooperate to promote a gene’s expression.
what is the purpose of MicroRNA’s and what does it lead to and can block?
They prevent genes from being translated by binding to the mRNA, leading to their degradation
can block translation
A group of proteins called the ______ removes _____ before ______, and it can remove some exons as well.
By regulating which ______ are included in the final mRNA transcript, cells can generate many proteins from a single gene. This process is called ______ ______.
A group of proteins called the spliceosome removes introns before translation, and it can remove some exons as well.
By regulating which exons are included in the final mRNA transcript, cells can generate many proteins from a single gene. This process is called alternative splicing.
Proteins have diverse functions and changes can affect. What are they?
–Cell structure
–Ability to catalyze enzymatic reactions
–Cell to cell signaling
–Ability to respond to other molecules
____ to DNA can alter the structure of proteins
mutations
what kind of mutation affect cells in the body of an organism; not heritable?
somatic mutations
what kind of mutation affect gametes; heritable and relevant to evolution?
germ-line mutations
Different mutations arise in humans at different rates.
While small mutations are more common, large mutations end up _________________?
introducing more mutated bases into a population
Germ-line mutations are rare, but accumulate in populations over time
they are the raw material for what?
evolution
In diploids, ______ __ may be masked by the presence of a ____ ____ ____ ____ ____ on the other chromosome
In diploids, deleterious mutations may be masked by the presence of a functional copy of the gene on the other chromosome
**Concept to remember **
Genetic changes in gene expression arise when noncoding mutations affect where, when, and how much a gene is transcribed
Among sexually reproducing organisms, like humans, males and females combine their gametes to reproduce.
During the production of gametes, each pair of chromosomes crosses over and exchanges segments of DNA, in a process known as what?
genetic recombination (crossing over)
Each gamete receives only one copy from each pair of chromosomes. As a result, each child carries a unique combination of the DNA of his or her parents. Along with independent assortment (next slide), ——– increases genetic diversity by producing ——–.
recombination
novel combinations of alleles
what occurs during meiosis in sexually reproducing eukaryotic organisms and produces gametes with a mixture of maternal and paternal chromosomes
independent assortment
what generates considerable genetic variation and its two techniques?
Meiosis
- Recombination
- Independent assortment
what results in great genetic diversity among offspring?
fusion of egg and sperm
**Linking genotype and phenotype
**
——: the genetic make-up of an individual
——: an observable measurable characteristic of an organism
- Genotype
- Phenotype
what is a result of an organism’s genotype and the environment?
Phenotypes
what often result from a developmental threshold mechanism?
Polyphenisms
quantitative traits
Study of their inheritance and evolution is called ——
quantitative genetics
Evolutionary biologists study variation in the ——–
expression of phenotypic traits
**Environmental Influences on Gene Expression
**
what changes in phenotype produced by a single genotype in different environments?
Phenotypic plasticity
- tailors organisms to environment
Phenotypic Plasticity is not the same as Natural Selection. PP is the flexibility for a population to show a —- term response to ——. NS is a —– term change in genes that allows a long-term response to ——- stimuli.
PP is the flexibility for a population to show a short-term response to stimuli. NS is a long-term change in genes that allows a long-term response to changing stimuli.
Gene expression often influenced by what?
and allows match to what?
Gene expression often influenced by signals from the environment
Allows match to environmental circumstances
what is natural selection?
mechanism that can lead to evolution, whereby differential survival and reproduction of indiciauls cause some genetic types to replace (outcompete) others
character state similarity not due to common descent
homoplasy
——: independent evolution of similar trait
——: reversion back to an ancestral character state
Convergent evolution
Evolutionary reversals
Principle of Maximum Parsimony
The alternative requiring the fewest evolutionary steps is usually best.
If more than one tree is equally parsimonious we can construct a Consensus Tree
Feathers are an ——–; they evolved originally for functions other than flight
Feathers are an exaptation; they evolved originally for functions other than flight
Pseudogenes are —–
Non-functional
**Concept to remember **
In genetics, a centimorgan (abbreviated cM) is a unit for measuring genetic linkage. It is often used to infer distance along a chromosome. However, it is not a true physical distance.
what kind of process is natural selection?
the process in nature by which organisms better adapted to their environment tend to survive and reproduce more than those less adapted to their environment
Survival in the struggle for existence is not random but depends in part on the hereditary constitution of the survival individuals. This unequal survival constitutes the process of natural selection. Over the generations this process of natural selection will lead to a continuing gradual change of populations, that is, to evolution and to the production of new species.
