ib biology unit 3

3.2.U.8 list mechanisms by which a species chromosome number can change

(1) chromosome splitting will increase the number of chromosomes (result: 2 chromosomes formed when there was previously 1 chromosome) (2) chromosome fusing will decrease the number of chromosomes (result: 1 chromosomes formed when there was previously 2 chromosomes)

3.1.U.3 state a similarity between alleles of the same gene

(1) found at the same locus on a chromosome (2) have MOSTLY the same nucleotide sequence (2) code for the same type of protein

3.2.U.4 list three ways in which the types of chromosomes within a single cell are different

(1) size ; number of base pairs (2) which genes they carry (3) location of the centromere

3.1.A2 state the number of genes in the human genome

(estimated) 20,000-25,000 genes in the human genome

3.2.U.4 state the number of nuclear chromosome types in a human cell

23 types of chromosomes males: Y chromosome 22 autosomes 2 types of sex chromosomes

3.2.A1 outline conclusions drawn from the images produced using Cairn's autoradiography technique

Cairn was able to see that prokaryotic chromosomes are circular. he also observed DNA replication occurring at the replication fork

3.2.A1 describe Cairn's technique for producing images of DNA molecules from E. coli

Cairn's radioactively labeled DNA to produce images of the molecule; this allowed humans to visualize and measure the length of DNA steps Cairn took: (1) DNA was replicated many times in the presence of radioactive thymine. as a result, the DNA now contained radioactive thymine nucleotides (2) the radioactive DNA was left for a period of time, covered with a sheet of photographic film, making the radioactive thymine exposed to the film (3) the radioactivity of the film exposed the DNA, leading to an image of the DNA. in Cairn's case, he observed circular DNA of a bacterial cell

3.2.U.10 outline the structure and function of the two human sex chromosomes

X chromosome: largest of the two sex chromosomes; length of 156 million base pairings and 1805 genes Y chromosome: smallest of the two sex chromosomes; length of 57 million base pairings and 460 genes

3.1.A1 state the cause of sickle cell anemia, including the name of differences in the Hb alleles.

a base substitution mutation occurs, a change to the base sequence of mRNA transcribed from it, and a change to the sequence of a polypeptide in hemoglobin normal hb: circular sickled hb: shaped like a crescent moon

3.2.U.9 describe the process of creating a karyogram

a cell is "frozen" in metaphase of mitosis by the applications of chemicals that disrupt the mitotic spindle. a hypotonic solution is added; water enters the cell, causing it to swell and burst, separating the chromosomes from one another. the chromosomes are stained and viewed with a microscope. a photo of the chromosomes is taken and used for organization

3.1.U.7 state the aim of the Human Genome Project and outline two outcomes of the Human Genome Project

aim: determine the sequence of the 3.2 billion base pairs and identify the locations of the (estimated) 20,000-25,000 genes outcomes: (1) identifies (estimated) 3 million human genetic variations, (2) developed new ways the study and examine genomes, and (3) led to the genetic sequencing of model organisms

3.1.U.3 define allele and list two examples of genes with multiple alleles

allele: different forms of a specific gene ex: blood type and pea color

3.1.U.4 state the difference between alleles of the same gene

alleles are different from each other in the sequence of nucleotides, can vary by just one base (called a single nucleotide polymorphism / intersection / deletion)

3.2.U.10 outline gender determination by sex chromosomes

biological sex is determined by which sex chromosomes are present XX = female XY = male the male parent determines the sex of the offspring, by passing either an X chromosome (making the offspring a female) or by passing a Y chromosome (making the offspring a male)

3.1.S1 outline information that can be determined given gene sequence alignment data

can be used to measure evolutionary relationships between species. the more similar the two sequences, the more closely related the species

3.2.U.9 list the characteristics by which chromosomes are arranged on the karyogram

chromosomes are photographed and arranged by size (largest to smallest), banding pattern, and centromere position

3.1.S1 explain why cytochrome oxidase 1 is often used to assess the differences in the base sequences of a gene between two species

cytochrome oxidase 1 is used to compare gene sequences between species because (1) the gene is present in the majority of eukaryotic species and (2) the gene has been sequenced for many species and is therefore accessible for genome database

3.1.A1 state the difference in amino acid sequences in transcription of normal and mutated Hb mRNA. outline the consequences of the Hb mutation on the impacted individual.

differences: normal (ATGC sequence), mutated (AUGC sequence) in mRNA consequences: increased rate of blood pressure, fever, metabolic disturbances, pain

3.2.U.6 define diploid and state the human cell diploid number

diploid: cell or organism contains two complete sets of chromosomes, one from each parent human cell diploid number: 2n = 46 (there are two (2) of each chromosomes (n) for a total of 46)

3.2.A4 describe the use of a karyogram to diagnose down syndrome

down syndrome is called a nondisjunction of chromosome #21, resulting in three #21 chromosomes, which can be observed in a karyogram

3.2.U.7 list example haploid cells

eggs and sperm

3.2.U.3 describe the structure of eukaryotic DNA and associated histone proteins during interphase (chromatin)

eukaryotic DNA is linear and associated with histone proteins in a structure called the nucleosome. during interphase, the DNA is not supercoiled into chromosomes, rather in a loose form called chromatin

3.1.U.5 state the source of new alleles of a gene

formed through mutations in the DNA sequence of a gene

3.2.U.6 outline the formation of a diploid cell from two haploid gametes

gamets (eggs and sperm) are haploid, meaning they have ONE complete set of chromosomes. when the games fuze during fertilization, the two sets of chromosomes (one from the eggs and one from the sperm) combine to create a diploid zygote

3.1.U.2 define gene locus

gene locus: specific position of a gene on a chromosome

3.1.U.1 define gene

gene: a heritable gene of factor that influences or controls a specific characteristic, consisting of length of DNA occupying a particular position on a chromosome

3.1.U.6 define genome

genome: complete set of genes and genetic material present in a cell or an organism

3.2.U.7 define haploid and state the human cell haploid number

haploid: cell of organism contains one one set of chromosomes, no chromosomal pairs human cell haploid number: n = 23 (there is one of each chromosomes (n) for a total of 23 chromosomes)

3.2.A3 explain the relationship between the number of human and chimpanzee chromosomes

humans have 46 chromosomes and chimpanzees have 48 chromosomes. studies show that two chimp chromosomes fused together, creating one human chromosomes (chromosome #2 in humans)

3.2.A3 explain why the typical number of chromosomes in a species is always an even number

in sexual reproduction, each parent usually gives a set of chromosomes, which results in an even number of chromosomes distributed ex: parent one- 13n parent two- 13n total- 2n = 26 (EVEN NUMBER)

3.2.A4 distinguish between a karyogram and a karyotype

karyogram: graphical/photographical representation of the karyotype karyotype: characteristics of an individual's chromosomes (number, type, shape)

3.2.A3 state the minimum chromosome number in eukaryotes

minimum number: 2n = 2

3.2.U.1 define the term "naked" in relation to prokaryotic DNA

naked: referring to the DNA not being surrounded by histone proteins

3.2.U.1 describe the arrangement of prokaryotic DNA (nucleoid and plasmid)

nucleoid: the main DNA of the cell, not inclosed in membrane, double helix forms a loop, isn't wrapped around histone proteins plasmid: additional loop of "naked" DNA found in some prokaryotes, smaller than main nuclear DNA, replicated identically

3.2.U.8 state that chromosome number and type is a distinguishing characteristic of a species

organisms with differing numbers of chromosomes are not likely able to interbreed; all members of the species will have the same number of chromosomes

3.2.U.2 describe the structure and function of plasmid DNA

plasmid: small circular loops of double helix DNA, replicated independently of the main nuclear DNA, carry genes that allow bacteria to become resistant

3.1.U.7 define "sequence" in relation to genes and/or genomes

sequence(noun): the order of nitrogenous bases in a gene or a genome (ex: ATGCTGAGCT) sequence(verb): the process of determining the order of nitrogenous bases in a gene or genome

3.2.U.5 state a similarity and a difference found between pairs of homologous chromosomes

similarities: (1) same genes at the same locus (2) majority of the same DNA base sequence (3) same length (in base pairing) (4) same centromere position (5) same staining pattern differences: (1) different origin (2) different alleles of the gene

3.1.U.5 describe a base substitution mutation

substitution mutation: replace one gene for another the new allele that results from the mutation might... (1) causes a small change in the protein produced by the gene- missense (2) have no effect by the protein produced by the gene- silence (3) cause an incomplete / nonfunctioning protein to be produced by the protein- nonsense

3.2.U.3 explain why chromatin DNA in interphase is said to look like "beads on a string"

the base unit of chromatin is the nucleosome connected by sections of linear DNA. the structure gives the appearance of beads on a string

3.1.U.6 state the size in base pairs of the human genome

the human genome is composed of about 3.2 billion pair bases, within the 23 chromosomal pairs and mitochondrial DNA

3.2.A3 explain why the chromosome number of a species does not indicate the number of genes in the species

the number of chromosomes does not indicate the number of genes. it is possible to have one large chromosome with many genes, or a smaller chromosome with fewer genes, vise versa

3.2.A2 describe the relationship between the genome size of a species and the species complexity in structure, physiology and behavior

there is a great variety of genome size. in general, eukaryotes have larger genomes than prokaryotes. however, the genome size does not seem to correlate with the complexity of the organism.

3.2.U.6 state an advantage of being diploid

there is a second copy of the allele, that may be able to counter the negative versions of chromosomes

3.2.A4 deduce the sex of an individual given a karyogram

to determine the sex of an individual, examine the last set of chromosomes on the karyogram XX: female XY: male

3.2.U.5 define homologous chromosome

two chromosomes, one paternal origin and one maternal origin

3.1.A2 describe the relationship between the number of genes in a species and the species complexity in structure, physiology and behavior

within plants and animals, there is correlation between complexity and the number of genes