Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

yr.11 Human Biology > DNA, mitosis, stem cells > Flashcards

DNA, mitosis, stem cells Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

mtDNA

A

Mitochondrial DNA, 5-10 mtDNA molecules in mitochondria
1% of total DNA
Found in Mitochondria
forms circular DNA molecule
37 genes, 24 for making tRNA, 13 for making enzymes necessary for cellular respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

DNA structure

A 
Is a polymer (molecule of many repeating units)
made of nucleotides
in form of strands
Two strands twist into double helix
2-3m long 1 millionth of m thick 
Order of bases determines genetic code.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

nucleotide

A

Small repeating units
composed of: deoxirybose, phosphate group, nitrogenous base
Sugar molecule of one nucleotide bonds phosphate group of another one
two strands join by specific nitrogenous bases being attracted to one another by weak hydrogen bonds
Up to 2 million codes
average chromosome is made of 140 million base pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Types of nitrogenous bases

A 
adenine
Thymine 
cytosol
guanine
Uracil (RNA)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Chromosomes

A

super-coiled structures
Made when cells divide
large enough to see with light microscope
46 in each human cell
Each chromosome is made up of sections of DNA that code for particular proteins
each section called a gene.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Chromatin

A

DNA when cell isn’t splitting

Forms tangled network in nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Histone

A

Protein in which DNA wraps around to form nucleosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

RNA

A

Ribonucleic Acid
Sugar molecule is Ribose not Deoxyribose, ribose has 1 more oxygen atom
RNA is single stranded
Has uracil no thymine
Strand able to fold on itself, forming hydrogen bonds between complementary bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

types of RNA

A

mRNA
rRNA
tRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

mRNA

A

messenger RNA
Made in nucleus and takes genetic code into cytoplasm allowing genetic code into cytoplasm allowing genetic code to be ‘read’ by ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

rRNA

A

Ribosomal RNA
60% of ribosome mass, other is protein
Ensures correct alignment of mRNA, tRNA and ribosome
also has enzymatic bonds between amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

tRNA

A

Transfer RNA
contains 70-90 nucleotides
Each tRNA is able to carry specific amino acid, therefore plays vital role in protein synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

start codon

A

AUG

Methionine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Stop codon

A

UAG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Transcription

A

process by which genetic instructions are copied from DNA to RNA
Transcription triggered by chemical messengers entering nucleus from cytosol and bind to relevant genes on DNA
Helicase enzyme seperates strands, usually 17 bases at time
RNA Polymerase then copies on one strand to create a strand of mRNA wt identical information as parent strand.
Often many polymerase follow first to make many copies at once

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

template strand

A

Strand that is copied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

coding strand

A

Other strand

bases on strand will be identical to mRNA (except for uracil and thymine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Translation

A

production of protein using info coded in mRNA molecule
In cytosol, ribosome attaches to one end of mRNA at start codon
ribosome then moves along mRNA 3 bases at a time
As ribosome reads codons on mRNA, tRNA with complementary bases join to mRNA
amino acids carried by tRNA are joined so protein is assembled wt amino acids in correct sequence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Gene expression

A

process of copying info from DNA onto mRNA, then translating the message into a series of amino acids to form protein
Cell is producing mRNA based on the cell’s purpose.
cell can produce up to 150 000 proteins per second
Genes used are ‘switched on’
genes not used are ‘switched off’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Factors affecting gene expression

A 
age of cell
Time of day
signals from other cells
Environment of the cells 
whether or not cell is dividing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Lipid and carbohydrate synthesis

A

require no genes, however require enzymes
Enzymes are proteins
thus indirectly genes control synthesis of lipids and carbohydrates

22
Q

Epigenetic

A

inheritance of factors that make genes more or less likely to be expressed
Changes in gene expression resulting from mechanisms other than changes in the genes

23
Q

genome

A

Hereditary info coded in DNA

24
Q

Epigenome

A

Sum of all factors determining where, when and which genes are expressed
therefore controls what proteins are synthesised
Epigenetic factors tell types of cells how to behave
Epigenome can change due to exposure to environment stimuli. These don’t change DNA but interfere transcription and translation

25
Q

chromatin

A

For DNA to fit in nucleus, must be tightly coiled
when cell not dividing DNA forms tangled network
DNA and histones referred to as chromatin
Gene expression may change if way DNA is wrapped around Histone

26
Q

Types of gene expression based on histone

A

change of amino acids in histone
Acetylation
DNA methylation
Histone Methylation

27
Q

Change in amino acids in Histone

A

histone shape will change
Modified shape is copied when no new molecules are formed
ensures stem cells changed into specific cells remains that specific cell

28
Q

Acetylation

A

addition of acetyl group to histone protein
Reduces attraction of DNA and histone, relaxing structure of chromatin
promotes transcription by allowing RNA polymerase access
acetylation enhances gene expression

29
Q

DNA methylation

A

Occurs by adding methyl group to DNA or Histone
occurs where cytosine is adjacent wt guanine, known as CpG sites (cytosine-phosphorus-guanine)
Methylation prohibits gene expression by restricting access to RNA polymerase

30
Q

Histone methylation

A

Increase/decrease transcription of genes. Depending on where methyl group attaches and how many attach
if methylation causes chromatin to relax, transcription increases

31
Q

need for cell reproduction

A

Cells don’t grow, therefore more cells needed
new cells needed to replace old, dead, damaged cells
More wear and tear on cell, the shorter the life span

32
Q

phases of cell cycle

A 
G1
S 
G2
M
G0
33
Q

G1 phase

A

Cell produces new proteins, grows and carries out its normal tasks
phases finishes when DNA begins duplication

34
Q

S phase

A

Synthesis phase

DNA molecules in nucleus form exact copies of each other

35
Q

G2 phase

A

Second growth phase

36
Q

M phase

A

Mitotic phase

Cell divides into two daughter cells

37
Q

G0 phase

A

When cells leave the cell cycle and stop dividing

38
Q

mitosis

A

Cell division
division of nucleus
Ensures each body cell receives exact same hereditary material (DNA) as parent cell
process is continuous, doesn’t occur in steps

39
Q

Stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

40
Q

Interphase

A

period between cell divisions

Goes through G1, S and G2 phases

41
Q

prophase

A

Two pairs of centrioles and opposite poles are visible, microtubules begin to radiate from them
nucleolus disappears and nuclear membrane begins to breakdown
Chromatin threads of DNA become tightly packed into chromosomes
coiling of DNA makes it easier to distribute DNA to daughter cells

42
Q

Metaphase

A

chromatid pairs line up on the equator of the spindle

Centromere attaches to a spindle fibre

43
Q

Anaphase

A

Each pair of chromatids separates at the centromere

chromosomes are pulled towards opposite poles of cell

44
Q

Telophase

A

Two sets of chromosomes form tight groups at each pole
nuclear membrane forms around each group, nucleolus appears in each new nucleus
Spindle fibre disappear
chromosomes gradually uncoils to become chromatid

45
Q

Cytogenesis

A

division of cytoplasm during telophase
Furrow develops between two nuclei, gradually deepens until it cuts cytoplasm into two parts, each with own nucleus
This along with mitosis results in 2 daughter cells

46
Q

differentiation

A

Process by which cells become specialised
during mitosis, different genes become activated, making stem cells into specialised cells.
Specialised cells can divide therefore replaced by other means
when stem cells undergo mitosis, daughter cells might be stem cell (stem cell proliferation) or differentiate

47
Q

Stem cells

A

cells that undergo differentiation
Not specialised for any role
capable of repeated division by mitosis
Potential to develop into any cell type means can provide unlimited source of cells for repair

48
Q

stem cell types

A

Totipotent stem cells
pluripotent stem cells
Multipotent stem cells

49
Q

totipotent stem cells

A

Potential to create any type of cell necessary for embryonic development

50
Q

pluripotent stem cells

A

Can give rise to any of the cells in the body

embryonic stem cells are pluripotent

51
Q

Multipotent stem cells

A

potential to form a number of different types of cells

Eg. Blood stem cell makes red, white and platelets

yr.11 Human Biology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions