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What is the difference between sexual and asexual reproduction?
Sexual- require two parents plus sperm and egg
- Asexual- only require one parent
- example plants
How does binary fission work, and what cells do this?
- Takes 1 chromosome and one compy of
- each gene (haploid) in prokaryotic cell
What is the cell doing during interphase in eukaryotic cells?
- This is called the cell cycle where
- the cell grows, develop, and replicates itself.
G1-grow more proteins and organelles
s- dna is replicated
- g2-more proteins synthesized
- metabolic activity
What is chromatin?
- Where chromosomes are composed
- consisting of protein, rna and dna
- A threadlike structure of nucleic
- acid and protein found in the nucleus of most living cell, carrying genetic
- information in the form of genes.
What is a sister chromatid?
- Sister chromatids-the two identical
- copies of a chromosome resulting from DNA replication and held together by a
What is a centromere, and what does it bind together?
Binds together sister chromatids
What are the 3 functions of mitosis?
- Growth, cell replacement, asexual
The single function of meiosis?
- It the key function of the sexual
- cycle in a eukaryotes.
- Meiosis is the stage of the sexual
- cycle in which a diploid cell, ordinarly having two complete sets of
- chromosomes. Two such gametes arising from different individual organisms may
- fuse by process of fertilization to generate a new diploid individual, thus
- completing the sexual cycle.
Describe the phases, chromosome number and movement during interphase
4 phases –
- Prophase/prometaphase –-Chromatin
- condenses to sister chromatidsconnected by centromere -Centrosomes(areas of
- microtubule organization) move towards opposite ends of the cell4
- PROMETAPHASE Nuclear envelope
- dissolves -Microtubules extend from centrosomes to connect with chromosomes and
- each other -Chromosomes are moved toward center of cell as spindle attaches
- Metaphase –Chromosomes lined up with
- their centromereson metaphase plate -Microtubules attached to sister chromatidscome
- from centrosomeson opposing sides -Other microtubules attach to each other
Chromatidsaligned on metaphase plate
Metaphase: The chromosomes align at the metaphase plate.
- Anaphase –Centromeres come apart, so
- -Sister chromatids separate and are pulled toward opposite centrosomes
- -ATP-powered proteins (kinetochores) move sister chromatids along microtubules
- -Microtubules attached to chromatids shorten -Other microtubules lengthen,
- elongating the cell
- Anaphase: The chromosomes split and the kinetochore microtubules
- Telophase, -Nuclear membrane forms
- around two chromosome groups -Chromosomes uncoil into chromatin -Mitotic
- spindle disappears
- Telophase: The decondensing chromosomes are surrounded by newly
- formed nuclear envelopes. Cytokinesis has already begun; the pinched area is
- known as the cleavage furrow.
- cytokinesis(cell division) Cleavage furrow
- forms from, eventually creating two daughter cells
- Plant cells have cell walls, so
- cytokinesisoccurs differently
How is cytokinesis different in plants and animals?
- Animail-clevage forms creating tow
- daughter cells
- Plant-Vesicles carrying cell wall
- material fuse between the two daughter nuclei, forming cell plate, which
- eventually grows into the new cell wall.
In which phase of the cell cycle does an organism spend most
of its time?
What are anchorage dependency and density dependency in cell
- •Anchorage dependent-cells must be
- in contact with solid surface to divide
- •Density-dependent inhibition –cells growing on
- a surface grow until they form a single layer, then stop dividing
What does the cell cycle regulate, and how does it work?
What is wrong with cancer cells?
- Cancer cells divide excessively
- because they do not have either density-dependent inhibition or anchorage
- dependency (or both)
What is a homologous chromosome?
Come form mother and father
- •Same loci (position) •Potentially
- different instructions (alleles) for each copy
How is that different from a sister chromatid?
- Because sister chromatids are
- identical copies
What is the difference between a centrosome and a
- Centrosome- is a spherical cell
- organelle present near the nucleus. It initates the process of cell divison and
- froms the basal bodies of cilia and flagella.
- Centromere- is the condensed region
- on the chromosome. It is the site where the spindle fibers attach during cell
What is the spindle, and what is it made of?
What is a locus?
- Is the specific location of a gene,
- dna sequence or position on a chromosome.
- Physical and functional heredity
- One or two versions of a gene. An
- individual inherits tow alleles one from each parent. (homozygous)=two alleles
- the same.
How many copies of each homologous chromosome does a
haploid, diploid, triploid, and tetraploid organism have?
- diploid- Humans are diploid-they
- have 2 copies of each gene Nomenclature: “diploid number 2n= 46”
haploid-one set of chromosomes
- triploid- have a extra set of
teraploids--4 copies of each gene
Describe chromosome number and movement during meiosis I and
- Meiosis 1- homologous chromosomes
- line up together on the metaphase plate, and sister chromatids stay together as
- each set moves in opposite directions
- Meiosis2-sister chromatids line up
- together on the metaphase plate and later split up
What are gametes, and how many
chromosomes do they contain relative to a non-reproductive cell?
Gametes (sperm and egg cells)
What is fertilization?
- Fertilization – haploid sperm and
- egg cells fuse to form diploid zygote
How is mitosis
different from meiosis?
- Mitosis- Chromosomes are evenly
- divided into two daughter cells, this ends when cell divides asexual
- Meiosis- sexual reproduction, One
- cell produces 4 daughter cells (vs. 2 for mitosis
Generating genetic variation: What is independent orientation of
What is random
- Any egg can be fertilized by any
What is crossover?
- The exchange of genetic material
- between non sister chromatids during synapsy of prophase 1 of meiosis
What is a karyotype, and what can it tell you?
- A picture used to see all
- chromosomes Is used to identify and evaluate the size, shape, and number of
- chromosomes in a blood cell. It can tell you of any abnormalities.
Autosomes vs sex
chromosomes What is a nondisjunction, and what are the consequences for the
- Autosomes- Numbered from largest to
- smallest; Identified by size, position of centromere
- Sex chromosomes- One pair in humans
- (most common); XX for females, and XY (Y is very small) for males
Potential exam question:
Explain how trisomy resulting from a nondisjunction is different from a
triploid organism. Potential exam question:
In a particular cell, there are two copies of chromosome 1: one from the
organism’s mom “C1mom” and one from the organism’s data “C1dad”, and two copies
of chromosome 2: one from the organism’s mom “C2mom” and one from the
organism’s data “C2dad”. a. What is the ploidy of this cell (e.g., haploid,
diploid, tetraploid, etc.)? b. Draw this cell and the arrangement of
chromosomes that would occur during metaphase of mitosis. Be sure to include
all four chromosomes, the metaphase plate, and the centromeres. c. Draw the cells that would result from the
arrangement you showed in ‘b’. Be sure to include the cell membranes, the
nuclear membranes, and all cell contents. d. Draw this cell and the arrangement
of chromosomes that would occur during metaphase of meiosis I. Be sure to
include all four chromosomes, the metaphase plate, and the centromeres. e. Draw the cells that would result from the
arrangement you showed in ‘d’ after telophase of meiosis II. Be sure to include
the cell membranes, the nuclear membranes, and all cell contents.