Flashcards in Chaoter 6.1 Deck (43):
Give an example of an visible genetic difference
-Coat colour of llama
Give an example where the genetic difference isn't visible
What is genetic diversity?
-variation or inherited genetic difference in a species
Give 2 facts about genetic diversity.
-result of sexual reproduction
-randomly sorts, shuffles DNA
What is diploid number?
-Body cell that has two sets of chromosomes
What is the human diploid number?
How does mitosis help diploids?
-Makes sure diploid number always stays the same and genetic information contained in body always remain the same unless mutation
Why does genetic diversity within a species is more advantage than a species with no genetic diversity?
Organisms will have combinations of genes from parents, allow it to cope with changes in environment
What is haploid number?
One set of 23 chromosomes from female parent and one set of 23 chromosomes from their male parent
What are haploid chromosomes carried in
What are gametes?
Specialized cells necessary for reproduction
What are male gametes called
What are female gametes called
What is fertilization
The process which an egg cell is penetrated by a species cell and haploid genetic information from sperm and egg cells combine
What is a zygote
New diploid cell formed by fertilization,
Half chromosomes from female half from male
What is embryo
The stage of a multicellular organism following fertilization
What is the difference between a zygote and embryo
Zygotes undergoes mitosis
Cell division developes into embryo
What is meiosis
Process that produces sperms and eggs
Name the steps of meiosis
- Anaphase 1
- Telophase 1
Why is meiosis important?
Without meiosis, joining of sperm and egg cell during fertilization would produce offspring with two times original number of chromosomes
What are the homologous chromosomes
A pair of matching chromosomes
Describe the steps of meiosis 1
Prophase 1: homologous chromosomes pair up, crossing over
Metaphase1: homologous chromosomes pair up at equator
Anaphase1: homologous chromosomes separated by SPINDLE
FIBRES, independent assortment
Telophase1: one chromosome from
homologous pair at each pole of cell
Interkinesis: stage between cell division, cell grows and makes protein NO REPLICATION OF DNA
Describe the steps of meiosis 2
Prophase 2: one chromosome of homologous pair in each cell
Metaphase 2: chromosomes from single line across middle
Anaphase 2: sister chromatids move to opposites poles of cells
Telophase 2: spindle fibres begin to disappear, nuclear membrane forms around each set chromosomes
Cytokinesis: two daughter cells seperated
What is the result of meiosis 1
-2 diploid cells, 46 chromosomes
What is the result of meiosis
-4 diploids, 23 chromosomes
What is crossing over?
Parts of non sister chromatids "cross over" each other and exchange segments of DNA
What is the result of crossing over?
-Each chromosomes picks up new genetic information from the other
-multiple crossovers can occur between 2 chromosomes, can creat infinite genetic possibilities
What is independent assortment
-homologous pairs of chromosomes seperated and sort themselves into daughter cells; shuffling of genes
What happens during independent assortment
-homologous pairs of chromosomes seperate at equator and move towards opposite poles of cell
What is gamete formation in males
-Meiosis 1 occurs and produces 2 cells, followed by meiosis 2 if there's enough nutrients for cell division
-4 cells within cytoplasm and organelles equally divide among them
What is the gamete formation in females
Meiosis 1 occurs and produces 2 egg cells, unequal division of cytoplasm and organelles
After meiosis 2, threes egg cells disintegrate, one large egg cell remains most of cytoplasm, available for fertilization
Describe chromosome mutations in meiosis
-parts of chromosome can be inverted,
-parts of chromosome can be duplicated
-parts of chromosome can be lost or deleted
-parts of chromosome came move to a different region in the chromosome
When do chromosome mutations occur?
-cells exposed to mutagens (radiations or chemicals)
Describe mutations in meiosis 1 and meiosis 2
Meiosis 1: homologous chromosomes fail to seperate
Meiosis 2: sister chromatids fail to seperate
What is the result of mutations
-one gamete will have two copies of chromosomes, other will have no copy of that chromosome
What is a karotype?
Photograph that shows number of chromosomes a person has, the size, shape
What is karotypes for
Used to diagnose genetic disorders
How are karotypes prepared?
Cutting and pasting chromosomes from body cells during mitosis
How are homologous chromosomes identified (karotypes)
-paired by size, centromere location and banding patterns
What is a syndrome and give an example.
Particular disease or disorder with a specific group of symptoms that occur together
Describe people diagnosed with Down syndrome
-characteristic facial features, -
-prone to develope heart defects and disease (Alzheimer's, leukaemia)
What percent of people are caused by extra 21 chromosomes