Inheritance
What distinguishes living organisms from non living things?
The ability to reproduce their own kind
What is heredity?
The transmission of traits from one generation to the next
What is variation?
The difference in appearence or traits among offspring, parents, and siblings
What is genetics?
The scientific study of heredity and variation
Do you inherit your parents' physical traits directly?
No, only their genes, not their physical features themselves
What happens in asexual and sexual reproduction?
A single individual passed all its genes to offspring without fusion or gametes.
offsprings are genetically identical to the parent
What is a clone?
aa group of identical individuals produced from a single parent
How does sexual preproduction differ from asexual reproduction?
In sexual reproduction, two parents produce offspring with unique combinations of genes
How many chromosomes are in a human somatic cell
46, arranged in 2 sets of 23
How many chromosomes are in human gametes?
23 chromosomes or a single set
What are homologous chromosomes (homologs)?
Pairs of chromosomes that are the same length, shape, and carry genes for the same traits
What do homologs carry?
The same genes but possibly different alleles (versions of a gene)
What determines the sex of an individual?
The sex chromosomes, called X and Y
What arecthe sex chromosome combinations for males and females?
Male: XY
Female: XX
What are autosomes?
The 22 pairs of non-sex chromosomes in humans
What is a karyotype?
An ordered display of chromosome pairs from a cell
What does sexual reproduction involve?
The fusion of haploid gametes during fertilisation to produce a diploid zygote
What is a zygote?
A fertilised egg cell containing one set of chromosomes from each parent
What is the purpose of meiosis
To halve the ploidy wheb forming gametes
How does meiosis relate to inheritance?
It insures that offspring inherit one set of chromosomes from each oarent, maintaining species chromosome stability
Key steps in sexual reproduction?
Fusion of haploid gametes->forms a diploid zygote
Zygote divides by mitosis-> forms somatic cells and develops into adult
Gametes are produced by meiosis from gemline cells
Gametes contain only one copy of each chromosome
What happen before meiosis begins?
Chromosomes are replicated during interphase just like in mitosis.
How many cell divisions occur diring meiosis?
2, Meiosis I and Meiosis II
Howxmany daughter cells are produced in meiosis and how do they differ from mitosis?
4 daughter cells are produced, each witj half the number of chromosomes as the parent cell
Why is meiosis important?
It produces haploid gametes for sexual reproudction?
What happens during Prophase I
Homologs pair up and crossing over occurs
Chiasmata form where chromatids exchange genetic material
What happens durinf metaphaee I?
Tetrads (paired homologs) line up at the metaphase playe, and microtubulesc attacj to each chromosomes kinetochore from opposite poles
What happened in Anaphase I and Telophase I
Anaphase I: homologs move to opposite poles
Telophase I: each new cell has a haploid set of chromosomes but each still consists of two sister chromatids
Does DNA Replication occur between Meiosis I and Meiosis II
No.
How is Meiosis II similar to mitosis
Sister chromatids are seperated into different cells
What happens during metaphase II
Sister chromatids line up at the metaphase plate?
Due to crossing over in meiosis I, the chromatids are no longer genetically identical
What is the main difference in life cycles among organisms?
It depends on whether the organism is diploid or haploid for most of its life
What is the life cycle partern in most animals?
Animals are diploid for most of their lives with haploid gametes as a small part of the cycle
The diploid stage dominates and meiosis produces gametes for reproduction
What is the life cycle pattern for other eukaryotes like fungi and plants?
Some eukaryotes are haploid most of the time becoming diploid only briefly.
Certain plants alternate between diploid and haploid stages